https://wccftech.com/marvels-avengers-could-get-playable-x-men-characters-post-launch/

Mockup of a potential cross-over between Avengers and X-Men in the Marvel Cinematic Universe.

The roster of Marvel's Avengers may eventually go beyond the heroes usually associated with 'Earth's Mightiest Heroes'. In a roundtable interview attended by Wccftech, when asked specifically about potential X-Men character additions, Marvel's Avengers Creative Director Shaun Escayg said every hero is on the table as long as the developers can persuade Marvel that the character can be a valuable asset for the story. Each new hero will have his or her own arc, as requested by Marvel.