As far as I have seen it's just speculation based on what Hickman has shown interest in the past and that he is a big enough name to not be forced into shilling for the MCU if he didn't want to. It's also spins off the many parallels krakoa had with Attialn which itself spawned rumors that he was suppose to be on inhumans before they hit the ground and now that he has prematurely left the X-men he might go back.