Here are my original theories before the film came out:
I saw the movie last Thursday opening night, and I hit a few big key story points! So here is my amended ultimate theory that takes the film into account and will give all us fans to speculate what will happen in Episode 8 because there are unanswered questions.
30 years have passed since the Battle of Endor when the Rebel Alliance defeated the Empire along with the last of the Sith, Darth Vader and Emperor Palpatine. During those 30 years, much has happened: The New Republic was formed out of the Rebel Alliance with Princess Leia taking a high-level political-military leadership role while Luke, Han, Lando, Chewbacca taking lead roles with X-Wing StarFighters and Luke still leading Rouge Squadron where they would pair up (Luke & Lando, Han & Chewbacca) and take a certain area of the galaxy to root out the remnants of the Empire (Lando and Han make a deal that they would take turns using the Millennium Falcon when going on these missions).
The Empire has one last stronghold on the Outer Rim, the planet Jakku. They lure the New Republic to that planet. The Battle of Jakku begins. This was the biggest final battle that will shatter the Empire. Losing the battle, the general of the last Empire’s Star Destroyer, decided to drive it into the planet than to have the New Republic capturing them. So they fly straight into the planet where the impact is so strong that 1/4 of the Star Destroyer goes deep through the ground. The battle of Jakku is over, the New Republic forces have won the Galactic Civil War where the remaining Empire officials signed the Galactic Concordance.
Peace is achieved in the Galaxy as all the planets align themselves with the New Republic. Leia and Han are married and have their first born son, Ben. Luke grew tired of piloting and asked Leia and Han if he can take Ben as his first Padawan to learn the ways of the Force. Leia wants no part in learning the ways of the Jedi because of her busy role in the New Republic. But Luke convinces her to at least learn the basics of sensing the Force and others around that are force-sensitive. Peace was achieved in the galaxy, but Luke with Force Ghosts Anakin, Obi-wan, and Yoda believe that the New Republic should be protected by the Jedi Knights as it was in the Old Republic before the Jedi Purge conspired by Emperor Palpatine. Ben, growing up with his dad, mom, and uncle; they tell him everything about their past history including his grandfather Anakin on how he succumbed to the Dark Side. And then Luke defeating Darth Vader and redeeming his grandfather, Anakin. In Anakin's last breathing moments alive, he slains Palpatine. Luke informs Ben that they are the first steps in bringing balance to the Force, but Ben becomes extremely rebellious and doesn’t believe in the ways of the Jedi and feels that they actually disrupted the Force that Palpatine and his grandfather already balanced as the Galactic Empire. This causes strain to Han and Leia's marriage due to Ben's frustration and anger issues. Luke tries and tries to train Ben in the Jedi ways, but he ultimately fails. Ben is frustrated that his power wasn't growing quickly enough. Spearheaded by Leia, there is a mission to retrieve intel that one of the remnants of the Empire has plans for a new weapon. During this mission, Luke and Ben (age 15), now his first apprentice; are slicing and dicing stormtroopers. Ben feels extremely uneasy because he feels that he's killing his grandfather's troops; and then they come up against General Snoke, one of the last generals of this fallen Empire who is at the time, rising high in rank. Because Snoke is secretly the former Darth Plagueis, who was Emperor Palpatine's master in the past. Palpatine believed he killed him, but he didn't. He only severely diminished his dark side power.
Luke and Ben encounter Snoke. Snoke feels how powerful Luke and Ben are. So as they are facing each other, Snoke seduces Ben with the limited dark side power he has, but he didn't need much since he was already falling into the dark side. So he betrays Luke by attacking him and cutting off his right arm along with his prosthetic hand. He escapes with Snoke and they travel to the farthest reaches of the Galaxy to regroup. The mission is also a failure because they weren't able to procure the new weapon plans. This event destroys Han and Leia's marriage, so they become separated. Han was reluctant about the Force when he first met Luke, but then slowly accepted it. But when his son left his family with Snoke, Han lost hope and left the New Republic with Chewbacca. Leia, on the other hand was much stronger and stayed with the New Republic because she felt it was her duty and to somehow think of a way to get her son back. Luke, extremely disappointed with himself looks for advice from Force Ghosts Yoda, Ben, and Anakin. They recommend that he needs to regroup himself. Luke builds himself a new metallic prosthetic right arm and hand from 3-CPO that accelerates his coordination via the Force. He is seeking for answers, and the advice given by the Force Ghosts was that he should travel alone as the only Jedi alive to where the Jedi Order was founded, planet Tython. He leaves his sister, friends, and comrades that include R2-D2 and 3-CPO. R2-D2 puts himself in low-power which puts him in a non-functional state because Luke left them all. In Tython, he hopes that he can think of a way yo redeem Ben like he did his father and a strategy to rebuild the Jedi Order. Lando just lost two of his best pals, he decided to spend the rest of his days going back to leading Cloud City on the planet Bespin. He and his wife have a son, but during this time the remnants of the Empire are abducting babies, so they grow up in their military to become Stormtroopers because they needed to build their force and had no capacity to build a clone army like the past. So a small group infiltrate Bespin and abduct newborns including Lando's son and bring him to the outer reaches of the galaxy. He is designated as Stormtrooper FN-2187.
The New Republic is thriving and almost completely destroyed the remnants of the Empire. With both Luke and Han gone, Leia was actually pregnant again. And when her son left with Snoke, she knew she was pregnant but didn't want to tell Han and Luke since they were both at the lowest points in their life. Eventually she gave birth to a baby girl, Rey. Leia realizes that she cannot raise her while she's in the New Republic because of the force connection they will eventually have. When she's old enough, she would have learned the truth of everything that has transpired due to the Jedi, Dark Side, and the Force. Leia doesn't want her daughter to go through the same experience as her son Ben. Knowing what Yoda and Obi-wan did with Luke and herself when they wanted to hide them from their father Anakin; Leia makes the difficult decision to leave her on the planet Jakku under the watchful eye of Lor San Tekka, who is friend and ally to Leia, Luke, and the New Republic. Leia makes sure she takes Rey to Jakku around the age where she will barely remember her family. Rey's earliest memory, is her mother telling her that her family will come back for her as she sees her mother (Leia) and her playmate (3-CPO) leave in a shuttle.
Han and Chewbacca are back at it with their old ways before they ran into Obi-wan, Luke, and the Rebel Alliance. They are galavanting around the galaxy and they lose the Millenium Falcon a few times.
Lando is leading Cloud City on the planet Bespin and someone discovered Luke Skywalker’s original lightsaber that he lost when Vader cut his right hand off. This is the same lightsaber that belonged to Anakin. Lando has the lightsaber now and was on course to bring back to Leia, so it can eventually be given back to Luke when he comes from solitude or when they locate him. But as Lando was traveling with the lightsaber, Maz Kanata and her pirates seize his ship and take his booty (which of course includes Luke's lightsaber). Lando is distraught and retreats back to Bespin.
Ben is back in the far reaches of the Galaxy with Snoke. Ben has adopted the name, Kylo Ren which still acknowledges his family linage (S-ky-walker So-lo).
Kylo, Snoke, and the remnants of the Empire have grown exponentially in numbers and rename themselves the “First Order”. And their mantra is that they want to reclaim the Galaxy in the name of Darth Vader who wanted “Order” in the galaxy by bringing balance in the Force via the Dark Side. General Snoke becomes Supreme Leader Snoke with high level generals like General Hux on their side. Along with Captain Phasma leading the First Order Stormtroopers. Kylo has an elite group of followers called the Knights of Ren. These Knights were formerly the small Jedi Padawan group Luke was training, but Ben at the time was able to make them defect with the persuasive power of Snoke. That's why Luke was extremely devastated and didn't understand why this was happening. He is back in Tython honing in his Jedi skills to hoping to become as powerful as Yoda. The knights believe that if they collect relics of the Force, they would one day see Kylo as a true Sith Lord. Kylo and his Knights of Ren are adamant about recovering force-sensitive relics like Darth Vader's mask and Luke's Lightsaber.
Before Kylo Ren left Luke, Han, and Leia, he took Darth Vader’s melted mask and he made part of it to make his own. He also created his own crossguard lightsaber. Snoke trains Kylo and teaches him as much dark side knowledge as he knows. One day they will take their revenge by killing the last Jedi and the Resistance where Snoke (Plageuis) hopes to reclaims himself as a Sith Master and having Kylo as his apprentice. Snoke is not at the same level of Vader and Sidious in regards to the Dark Side of the Force because Sidious diminished it greatly from Plageuis. Therefore, Kylo and Snoke have the similar relationship as Ben Kenobi to Luke Skywalker when they first meet; instead to eventually master the dark side and become Sith. Therefore, Kylo and the First Order are in search for his uncle, Luke Skywalker. Back in the First Order’s homebase planet where they have been regrouping since they were the remnants of the Empire, the First Order created something much more devastating than the 2 Death Stars combined; Starkiller.
General Leia and the New Republic sense this new major threat, so they are now desperately looking for Luke as well. However, Luke is still in solitude hoping to find a way to bring back Ben and to rebuild the Jedi Order. Lor San Tekka, who is now actively practices the religion, the Church of the Force in a small village in Jakku, pinpoints Luke's whereabouts in a data disk. Leia sends her best pilot, Poe Dameron and his droid, BB-8 on a secret mission to acquire the data disk from Lor San Tekka. As she also acknowledges in her head that their path might cross with her daughter Rey. As Rey has grown up not knowing who her family origins are and is now a self-made individual who can take care of herself living her life as a lone scavenger. As she still awaits for her family to come back.
Poe makes contact with Lor and they make the exchange, however Kylo and the First Order arrive to the small village. Poe hides the data disk in BB-8 and sends him off. Kylo takes Poe as his prisoner and kills Lor along with the villagers because they worship the Jedi since they are members of the Church of the Force. During this massacre, Stormtrooper FN-2187 is torn between what he’s grown up to learn as a Stormtrooper versus him having a good moral compass. He witnesses Stormtroopers killing and he can’t take it anymore since he's only been on Sanitary duty and this was his first time as a ground force Stormtrooer. Back on the First Order Star Destroyer over Jakku, he frees Poe because he needs a pilot and they steal a Tie Fighter (Poe names him Finn) and crash land on Jakku.
Finn wakes up in the morning and checks the destroyed Tie Fighter to see if Poe is there, he's not and he grabs his jacket. Poe parachuted earlier and he couldn't find Finn in the middle of the night, so he left to look for BB-8, but had no luck so he went back to the Resistance. Finn, Rey, BB-8, Han Solo, and Chewbacca cross paths that lead them to Maz Kaneta's Castle on the planet, Takodana. They meet Maz as she looks closely in the eyes of Rey and Finn. She senses that they may be extremely important. Rey hears voices in the lower levels of the Castle and senses something in a treasure chest, it's Anakin and Luke's lightsaber. When she grabs the lightsaber, since she is force sensitive and the granddaughter of Anakin; a powerful sense of the Force erupts and emanates throughout the galaxy. As the Force Awakens because Rey is the true prophecy of the one who will bring balance to the Force. Have you felt it?