With Marvel's Phase 3 starting with Captain America: Civil War in 2016, I'm going to begin with it. At the end of the film, it would be great to tie-in to Captain Marvel. Doctor Strange is coming out the same year, but, his presence was pre-established on Captain America: The Winter Soldier (mentioned by Jasper Sitwell). So, I'd like to keep Civil War's post-credits scene as an origin story for a new character. The scene goes like these:
Carol Danvers in a S.W.O.R.D. base, while the events after Civil War are being displayed on a television. And Danver's boss shows up, telling her she's got a new assignment.
That's it. I think it would be awesome, and hopefully, Carol Danvers will be cast by the time Civil War is in post-production phase.
Next is, Doctor Strange. This is an interesting one, because Strange represents another side of the Marvel Cinematic Universe we haven't seen yet. Its more of a dark-cosmic side. With Thor: Ragnarok coming in 2017, it would be interesting to see this:
Stephen Strange has been missing. He's been exploring new places in the universe, and ends up in Hel. He hears voices, of an upcoming event, a crisis, and suddenly, comes back to Earth.
It seems like a nice set-up for Thor: Ragnarok, and another look at Strange's powers in a deep form.
Following Doctor Strange, is Guardians Of The Galaxy 2. Its weird to think of a good post-credit scene for this one, specially from what we got in the first film. So, I'm thinking... after two really important post-credits scenes, you could have a silly one for this movie, so I'm leaving it to James Gunn's imagination.
Next is... Spider-Man. Or Marvel's Spider-Man. Or Marvel's The Spectacular Spider-Man. Or Marvel's Spider-Man: The New Avenger. Whatever they're going to call it. You might think why I didn't create a post-credits scene with Peter Parker being bitten by a spider, and there is a good reason for it.
Marvel is making an origin story, but without origins. They can do the same as they did with The Incredible Hulk (2008 reboot), and we had Bruce Banner becoming the Hulk in the opening credits. You can do the same for Spider-Man.
So, a great post-credit scene for this movie, could just be Spider-Man being recluted for The Avengers. The same way Nick Fury went to Stark, or Stark went to General Ross to include the Hulk on the team, we could have Iron Man applauding Spider-Man's efforts to keep New York save from Spidey's enemy -yet remains unknown who's going to be-.
After Spider-Man, comes Thor: Ragnarok. I'd like to see what happened to Odin. But, that should be explained through the movie, not at the end. So, maybe at the end, we see a completely different and unexpected post-credit scene:
We see Doctor Strange, who suddenly has a vision: It's Thanos, and he has a new Infinity Stone. Doctor Strange is in the possesion of the Soul Stone, somehow, and realizes that Vision has the Mind Stone. Thanos is coming, and Avengers need to be assembled.
Amazing. I would love that scene.
The next film, probably the most epic film of all time, is Avengers: Infinity War - Part 1.
Don't expect The Avengers beating Thanos in Part 1. Think about how he's coming to place everything upside down.
After we see The Avengers defeated, possibly, a death Avenger, I want to see the most epic phrase of the team.
Tony Stark is taking the fault of the team's failure -as seen in the vision induced by Scarlet Witch in Age Of Ultron-, so everybody agrees on a better way of working together, which motivates Tony to say: 'Avengers... Assemble!'.
I really have no words for this one. Awesome.
I think its weird we're having a Black Panther solo film and Captain Marvel solo film in between Avengers: Infinity War event.
Black Panther is going to be a part of the Avengers team in the Part 1 of Infinity War, so, his solo film could be about him returning from being defeated by Thanos, only to defend Wakanda.
The post-credit scene could be him rejoining the team. As simple as that.
Captain Marvel is also an Avenger already, so, I think after her solo film, her post-credit scene could be this :
The Guardians Of The Galaxy come to Earth on their search of Thanos and the Infinity Gauntlet. S.W.O.R.D. targets The Milano -their ship- and Captain Marvel updates them with Thanos trying to destroy Earth.
After Infinity War: Part 2, the only thing left is to set-up Phase 4. This is really hard, because you start to think... Who is greater than Thanos, and Marvel has the rights to? I believe Fox is going to give back the rights of the Fantastic Four, and we get to see a decent version of Galactus. If not, we can have Kang The Conqueror.
Finally, we have Inhumans. This one is hard, but we can have like the Kree and the Skrull moving their fight to Earth. I'm not so confident about this one, because the rights of the Skrull aren't defined yet, if they belong to Marvel or to Fox's Fantastic Four. So, we'll wait until we see!