Here's a better question. If Marvel does get the X-Men back, what is there left to do with them? They've done 3 Magneto films, Hellfire Club, Days of Future Past, and will do Apocalypse, Deadpool, Gambit, and more. They'll run out of stories for the X-Men when they get the movies back that it'll just be "Been there, Done That"
Though right now, Marvel really doesn't know what to do with the Inhumans. They seem to push Medusa so much, that she's a different character now. She used to be a hard ass queen who pushed others for her way, and now she's the super caring caretaker, a rule that usually is designated for Crystal. Hell, they don't know which Royal Family to focus on, and they keep adding more and more new characters that the book becomes very unfocused.