We know that Fantastic Four and the integration of X-Men will play a huge role in the future of MCU, we just still don’t know what that future will look like.
Fantastic Four could introduce to us some huge Marvel bad guys, from Doctor Doom to celestial beings like Galactus. Most of their stories are space-oriented, so they could be some kind of replacement for Guardians of the Galaxy, in terms of space movies.
On the other hand, we have X-Men. There are so many X-Men characters that is hard to even begin to guess where they could start. That said, we have already heard the voice of legendary Patrick Stewart and his Professor X in the trailer for Doctor Strange in the Multiverse of Madness.
That probably means Doctor Strange 2 is going to really introduce X-Men to the MCU, and we can’t help but think Stewart won’t be the only Mutant appearing in the movie.
Also, there are some rumors that one of the characters barely showing is Reed Richards from Fantastic Four. That is further backed up by the fact that the new Doctor Strange in the Multiverse of Madness teaser confirmed the mention of the Illuminati. One of the members of the Illuminati in the comics is no other than Reed Richards.
With all these new characters in the MCU coming our way, the future of the Marvel Cinematic Universe looks really bright. We just have to wait and see how will Feige and the rest of the team sort it all out.