I'd be shocked if he came back. Admirable as it may be, it is a stupid decision when you're projected as the top back in the draft. There is too much upside to leaving. Saban will encourage him to leave since he will be a 1st rounder.
He has nothing left to prove. Heisman isn't guaranteed, he already has a ring, possibly two. A catastrophic knee injury derails all of that earning--I'd prefer to set my children financially and teach them responsibility another way than make a decision that could take that away from me.