CAUTION: SPOILERS BELOW FROM MCU FILMS(& TV SERIES) THAT HAVE ALREADY BEEN RELEASED AS WELL AS SPECULATION FROM UPCOMING FILMS!!!!!!!!
Disclaimer: I am NOT a Comic Book Purist and do not think the films or shows should be exactly like the comics. The greatest strength of the comics is the Shared Universe. The greatest weakness is the fact that it NEVER ENDS. Making a story adaptable to film is not only to appeal to a larger audience but to draw a distinction between the stories.
Stick with me, this article will come full circle. The MCU began in 2008 with the release of Iron Man. Nick Fury tells Tony he's not the world's only Superhero. Expanded upon in The Incredible Hulk when his origins were revealed as trying to re-create the Super Soldier Serum which was obviously expanded upon in Captain America: The First Avenger. Thor introduced the START of the stories that involve Earth and the Marvel Cosmic Universe. The Avengers Continued upon this involving Alien Armies, Loki, etc. What connected all those films? S.H.I.E.L.D., which has now crossed over into Agents of Shield, and post-Captain America Strategic Scientific Reserve(SHIELD) origins show, Agent Carter. Thor 2 introduced us to Guardians, Guardians led us to Thanos. Captain America 2 introduced us to the Falcon, Winter Soldier, expanded upon Black Widow's amazing character. We got the end of SHIELD(at least for now), the resurgence of HYDRA taking place in the TV show and Film Universe(Baron Von Strucker in post-credits of Cap 2 & [The Avengers: Age Of Ultron](movie:293035)). Ant-Man being a film we should be more excited for, is introducing us to the YOUNGER and current Ant-Man, Scott Lang, Portrayed by Paul Rudd, as well as the older, Hank Pym. John Slattery will be portraying Howard Stark in the film. Hayley Atwell will also reprise her role as Peggy Carter. Once again, in an attempt to fill in the Time gaps between The First Avenger and Iron Man. In a Shared Universe, this is only a smart thing to do, in my opinion. We're getting Daredevil, Luke Cage, Jessica Jones, Iron Fist, and their Team-up in The Defenders on Television. There is a lot of opportunity for film and television crossovers there. As far as the timeline goes, there will be about 100 years of Characters & Stories by the time the MCU is finished. (1940s-2030s(ish)
Kevin Feige has mentioned that he (and his team at Marvel Studios) have a plan for the Cinematic Universe through 2028. Presumably Agents of Shield, Agent Carter, Daredevil, Defenders SERIES will presumably be over by then considering it'll be about 12-15 years after those show's debuts. The Question is: After Avengers: Infinity War, how do you end the Cinematic Universe? Avengers: Infinity War Part 2 will be released in May 2019. Spoiler Alert, there's still about 9 years to go after that LOL. Between Now and Avengers: Infinity War Part 2, we have: [Captain America: Civil War](movie:994409), Dr. Strange, Black Panther, Thor: Ragnarok, Guardians of the Galaxy 2, Avengers: Infinity War Part 1, Captain Marvel, and Inhumans. That's a lot to swallow. If 3 movies a year is a thing for this studio, then by 2028, there's potential for 27 more films after Infinity War. 27!!!! Inhumans are already slowly being introduced on Agents of Shield, so Marvel is banking on that, Dr. Strange is a strong Solo character, Guardians can open up a lot of Cosmic stories with amazing potential on film, Captain Marvel will be a strong female lead, Ant-Man will probably be way more popular than people are anticipating, Hulk needs some strong outings with Mark Ruffalo, Avengers is bankable no matter which heroes are involved, and I think the original characters(THOR, CAP, IRON MAN, & HULK) should all get one last solo outing(if not also, another Avengers film) before hanging up the Hammer, Shield, Armor, or Gamma Radiation induced Rage. Here are some potential projects, I feel, you will MOST LIKELY see in those years ahead (This is pure hypothesis based on where the film series could go):
Doctor Strange Sequels - 2
Guardians Sequels - 2
Ant-Man Sequels - 1
Inhumans sequels - 2
Captain Marvel Sequels - 2
Black Panther Sequels - 2
Avengers Sequels - 3
Captain America Sequels - 1
Iron Man Sequels - 1
Thor Sequels - 1
Hulk Sequels - 2
Have you done the Math? = 19 Films
What could you do with 8 more films?
Considering that they probably have the manpower and Cash to do do 4 films a year, lets stick with the 3 films per year = 27-19 = 8 films left Formula. Let's not forget, we want to, as a Studio, have a big finish(In terms of solo films). You started with Iron Man, Who do you end with? Dr. Strange? Maybe. Punisher? Doubtful. Blade? Hardly. Ghost Rider? Definitely NOT.
Spider-Man is Probably Marvel Comics' most popular character. In the Comics, he is younger than the other heroes, always the baby of the bunch, comparable in abilities and whatnot, but always a young person's attitude, wittiness, and overall personality. It Brings the Avenger's back down to the level of the reader since Spider-Man is closer in age to the audience. If, after the Spidey-Summit SONY is having in January, There could be a deal struck with Disney to either Lease the Character out, or just give the rights back. IF, after this conference, the deal is struck with Marvel, or the rights go back, Spider Man will be re-booted and will most likely be seen in an Avengers film first. That doesn't mean he shouldn't have A Solo film or FILMS!!!! You can get his origin over with a few lines in an Avengers film and knock him back to Solo films and start him right off as Spidey. Do Your Sinister 6 Story, Throw in Venom & Carnage, Black Cat, and the likes of them, tie in some other Heroes from the Universe in one or two of them, hell if you're gonna make RDJ do 4 Iron Man films, and 4 Avengers Films, You're gonna want to do the same with Spider-Man and keep with the continuity. The Way Iron Man started your series, you use Spider-Man to end it. While all Culminating into a final AVENGERS FILM (AVENGERS 6: The Undiscovered Country).
Even after including 4 Spider-Man films that still leaves 4 films. What could they be? Punisher? Blade? The Runaways? Ghost Rider? Or will they be on TV or NETFLIX? Will any television characters get a film? Daredevil? Will any other unused characters get TV shows or Films? Could we get a Solo film for Black Widow? Hawkeye? Falcon? I doubt it, but anythings possible. What is the extent of Crossovers we'll see TV to Movie and vice versa. The biggest so far is Lady Sif and Nick Fury being in Agents of SHIELD(Also, obviously, Phil Coulson & Peggy Carter jumping from FILM to TV), and need I mention Agent of HYDRA, Jasper Sitwell?
Anyway, with 27 films(or more), and a 6 TV Series(so far), There are so many opportunities, not only for crossovers, but for new characters(both Hero and Villain). Regardless of whether Marvel/Disney get's the film rights back for Spider-Man, there are so many cool things that could happen over the nest 15 years. I may be right, I may be wrong, but here's to hoping that it lives up to our expectations.