The issue with the evolution deal. How will Hickman explain Graydon? Two mutants that had a kid come out human? Do Creed x Mystique reverse the evolutionary process? lol Hmm. I could honestly see that, but on a serious note, things seemed more messy than mutants automatically being a new evolution of the specifies.
Unless Graydon (if he ever comes up again for whatever reason) is retconned as being a late-blooming mutant with a gene that took ages to activate.