I like the idea of Jean coming back from the WHR.
I mean, yes she is the uber-Phoenix of the Crown, but we also know that she has many pieces and she exists on different planes at all times.

What if the Jean Grey/Phoenix that comes back is the part of Jean that was an xman? The one that's most human? The one that still wants to be on earth with her loved ones?

She would still be Jean Grey aka Phoenix and she would still be an Omega level mutant. But she would CHOSE to be on earth. Her White Phoenix self would still be doing Cosmic duties in the WHR. But the Human aprt would be on earth.

I'm rash and impulsive. It's a flaw.