Professor Xavier has been alive since 2017: His soul was found trapped by the Shadow King and Fantomex basically agreed of his own will to swap places, letting Xavier ride back to earth in his body while he stayed in the Astral Plane(this is emphatically Phantomex's choice.)

Xavier eventually created a new body for himself--a young, healthy version of his original, and went by X for a bit.

Hickman's run, which is starting with these two minis and will continue with Dawn of X, which will be Published in the titles X-Men, New Mutants, Excalibur, Fallen Angels(starring the anti-heroes, including the psychich ninja who Psylock switched bodies with forever ago as the new Psylocke, Betsy's inheriting the Captain Britain Title from her brother,) Marauders(about X-Men on the seas, not Sinister's lackies,) and X-Force.

Also, Apocalypse is one of the good guys now.