I know this title sounds crazy, but just hear me out. It's not as crazy as it seems.Not too long ago, Kevin Feige said the following about Spider-Man in the MCU.
Already in the MCU, you just don't know it yet is what I wanna focus on. I'm not at all saying this does apply to the X-Men and Fantastic Four properties, I'm just saying it could. I used to say that there was no place, but this idea has never occurred to me before. They would also be fully aware of who they all were. Marvel doesn't even need rights, FOX and Marvel could also come together for a project too. Unlikely of course, but still.
X-Men Cinematic Universe
I'm going to start with their current universe since [X-Men: Days Of Future Past](movie:203942) rebooted the franchise. We have [Deadpool](movie:38663), X-Men: Apocalypse, and Gambit coming to us next year. I'm sure all of these will be great movies. I didn't want them to be at first because I thought if they sucked, Marvel would get rights back. Yeah I learned pretty quick that it doesn't work like that. Chris Evan's Captain America and Hugh Jackman's Wolverine, that would be an awesome team up!
Marvel connection? Easy.
The Battle of New York
This changed the world forever in the MCU. Just as in the comics, if this was an Avengers story, it would have focused on their side of it. Okay, the comics would have randomly said 'meanwhile..' and briefly showed why the X-Men weren't fighting alongside the Avengers. Fans know that the world of Marvel is huge and everybody can't get together and fight every single time. So if Marvel were to get rights back, their explanation might be that the X-Men were simply somewhere else.
[The Avengers: Age Of Ultron](movie:293035)
I feel like Marvel is already keeping the door open for this idea. In the MCU, these two are Eastern European orphans. They did an amazing job not really leaving any gaps as far as I'm concerned. If they did have rights, one day their father Magneto finds them. An event as big as Ultron, some would still ask, where are the X-Men. During their fight with Ultron, I'd say they're fighting Apocalypse.
[Captain America: Civil War](movie:994409)
This one is fairly simple as far as the MCU goes. The mutant community wanted out of this whole Civil War the Avengers were going through. I know it was the whole superhero community, but Avengers led both sides. This would be no problem.
[The Fantastic Four](movie:34667) Cinematic Universe
I at first was not impressed with the whole concept of a new Fantastic Four. Especially with them being so young. The new trailer though, it got me. They are spot on with how the characters should be. The heroes anyway. I wasn't clear on how Doom got drastically changed.
Marvel connection? Ehh
These guys are a bit harder to do because I haven't seen the movie, therefore don't have an idea of their universe. There is plenty of great characters like Galactus (done right unlike last time), Silver Surfer, Annihalus, etc.
I'm not going to delve into the Fantastic Four like I did the X-Men. We have no idea where they are headed. To make a quick guess though, they would get their powers and become the Fantastic Four before The Battle of New York. They'll be in the Negative Zone on some mission during The Battle of New York.
I would have loved to see Ioan Gruffudd as Mr. Fantastic interact with RDJ's Iron Man. However, I'm willing to give Miles Teller a chance.