There was Earth-X, where everybody on the planet got super powers (although they seemed to go back and forth as to whether that made them mutants, inhumans, or something else.) For the most part if was an interesting story but it also showed how quickly a planet where everyone has powers can get out of control.One of the rarest futures ever seen in the MU (outside of 100% utopian ones) are ones where mutants are the majority or dominant on Earth. It's clear Marvel will never honor that, and isn't interested in making comics where the average person has three heads, or purple elephant skin, or tentacles for a face. This is probably another place where editorial's will is clear.
Oddly enough the X-men played a very small role. It seemed most of them basically went "oh hey! No more mutant persecution? Cool. I'm retiring."