The upcoming Avengers: Doomsday and Avengers: Secret Wars will be the proper launch of the mutants in the Marvel Cinematic Universe. Many mutants already exist in the MCU, but the wider X-Men family aren't yet part of the core universe, although they soon will be. However, it should also be said that we shouldn't get too attached to the mutants in the two planned Avengers films, as Marvel supposedly intends to recast many as part of its MCU refresh after the events of Secret Wars.
Speaking about this to Entertainment Weekly at New York Comic Con, James McAvoy, known for playing Professor X in several X-Men movies, has stated that he thinks the idea of recasts is exciting but that he also doesn't see Hugh Jackman being a casualty of this.
"Look, I'm excited to see what happens next. I was a fan before I was an employee and I'll be a fan again! You want it to be...I just can't wait for it to be...Oh no, that was going to sound bad. It's going to put a lot of pressure on people."
He adds on the Jackman front: "I was gonna say, 10 years from now — it's probably gonna be 10 minutes from now — when A.I. has taken over and playing all the roles, and there are no actors anymore, he will still be playing Wolverine. Even A.I. will be like, 'Nah, he got it! Nah!'"
McAvoy also discussed that he thought Colman Domingo would be an interesting recasting of Professor X, calling the idea "amazing".