Marvel Studios now has the X-Men in the fold, and fans have no idea how the mutants will make their way into the Marvel Cinematic Universe. One fan on Reddit has a pretty great idea for how to integrate the characters successfully. User Lyndonguitar writes that you could have the X-gene lying dormant this entire time and then some big event in a future movie would have them awaken the gene for starters.
Professor X would have been born way closer to modern times and been operating a school for kids with aptitude or potential before the gene becomes active. All the students had the gene but then experience their powers after the event that switches them on. Now, Xavier and Magneto as headmasters of the school would serve as a de-facto haven for people affected by the event that triggered the change so suddenly.
Best way for mutants to enter the MCU without any multiverses or continuity break-up + Spider-Man Daredevil theory from r/FanTheories
Many in the comments argue that one of the three snaps in Avengers: Endgame could provide that catalyst. But, the Eternals could also become a point where the big event that would kick off the mutant presence in the MCU could stem from. Kevin Feige has remained focus on delivering good films and pretty much refuses to tip his hand about these new acquisitions going forward.
Marvel fans can expect an unfamiliar future ahead for the X-Men movies. During the Hall H panel on Saturday night at San Diego Comic-Con 2019, Marvel Studios head Kevin Feige revealed the Phase 4 slate of the Marvel Cinematic Universe. The X-Men are not a part of that schedule, but Feige did allude to "mutants" being something that Marvel Studios is working on.
Feige spoke to IGN after the big Marvel Studios presentation at San Diego Comic-Con. He clarified that the use of the word "mutants" instead of X-Men was not a big deal, but that the company's approach to the franchise will diverge from previous films featuring these chacters. "Mutants and X-Men are interchangeable," Feige explained. "I just said mutants. But yes, whatever we do will be quite different than what's been done before."
20th Century Fox has been making the X-Men movies since 2000. The studio's 12 films output, which includes Dark Phoenix even though it was released after the deal was finalized. One film remains on the docket from that previous run; The New Mutants set to hit theaters in 2020. The franchise is all but a memory after the release of Dark Phoenix for most fans that have been reading the tea leaves.
In another interview, Feige expanded his comments about finally having the X-Men and Fantastic Four under the same roof as the rest of the MCU heroes. He's happy about the Disney and Fox deal, but the focus remains on putting out the best product possible. "I'm extremely excited about those characters and about bringing Marvel's First Family up to the platform and the level that they deserve," Feige said.