The X-Men are due to make thier appearance in the MCU, and there are a lot of theories as to how they will be integrated into the history of the franchise. Some have suggested that mutants will enter the MCU from a different universe, one that will be assimilated into the sacred timeline. However, another theory has emerged, suggesting that the X-Men have already been part of the MCU.
There have been multiple theories about how the X-Men exist in the MCU. Some have suggested that Charles Xavier is responsible for hiding mutants in the MCU, while others say that the mutants will slowly emerge now that The Blip has been undone. There is one theory that suggests that not only have mutants always existed in the MCU, but some sort of cataclysmic event wiped them out from the memories of the general public.
Mutants could have been present at key moments in the history of the MCU
The theory, brought forward by Reffit user u/capiak, posits that an event like M-day has already happend, where the Scarlet Witch wiped out the world’s mutant population, save a few core memebrs of the comunity that had been regulars of the X-Men franchise. The thoery states that such an event could have happened in the MCU, which in addition to wipin gout mutants, altered people’s memories of them as well.
The theory goes on to say that the X-Men have actually been present in the MCU since Phase One, an have been a major part of every events in the MCU, from Loki’s invasion to the Battle of Avengers Compound. It suggests that what we have been seeing so far has been an altered history, one that was created as a result of a mutant extinction event by someone like Scarlett Witch, who can manipulate reality.
The X-Men might be from a different universe altogether in the MCU
The X-Men that we have seen so far in the MCU have all hailed from different universes, and it might just be the case that it stays that wy in the MCU. Rumours have been the circulating that the X-Men might exist in a universe of their own, and might get syncretized with the Sacred Timeline after the events of Avengers: Secret Wars.
It is no known whether thise characters would be from any of the universe that we have seen before, or will it be an entirely new iterartion of the X-Men, but it is definitely indicated by a slew of points that the X-Men might make an appearacne in a different universe as a team before they make a full blown appearance in the MCU.
Deadpool & Wolverine is sure to shed some light on this, as it is the first feature lenght mutant story for the MCU, wich might give us a glimpse of how the MCU treats the mutants and how it wishes to incotrporate them.
