The thinking is Hank did this so he'd be perfectly logical and be better at his job as head of X-Force. But he didn't expect himself to go completely evil, so the new/old Hank is going to take his place.
Like I said, it's just a theory, one I'm not quite sure of, but it would explain things.
I keep thinking there's some explanation for Hank's behavior Percy is holding back until the very last second. The hints he dropped earlier that something was wrong with him.