10 Ways To Get The Fantastic 4 Into The MCU (That Wouldn't Suck)
7. Alternative Dimension Team-Up
The addition of the Fantastic Four to the MCU could create a world where there are just too many heroes. The swelling ranks of the Avengers, potentially incoming Defenders, various TV series characters, the Spider-Verse and more are all being poured into the same finite planet. Maybe the Fantastic Four just don’t fit.
In which case, do what comics do all the darn time and throw some alternate dimensions in there.
It only takes one science experiment gone wrong to start opening up rifts to other worlds. One of those worlds might just turn out to be inhabited by a superpowered foursome who serve their world much as the Avengers serve the MCU. Maybe they become temporary allies against a cross-dimensional threat, of which the Marvel universe has plenty - Mojo, Annihilus, Abraxes, Morlun, and a whole stack of others. Maybe a super-science crisis has two universes colliding, or one invading the other. A cross-universe team-up helps save the day.
Maybe, again, they just fight. Some Thing-on-Hulk fisticuffs would make for a hell of a trailer.