I think Mourinho will sell him, but he shouldn't as he has the intelligence and technical ability to be useful in several positions, his injury record is good (for a United player) and he played well all last season which is a fecking rarity in and of itself.
Yes, Mourinho said he prefers specialists, he did also add he liked to keep 1 or 2 around who could fill in several positions which is what Blind does, (LB, LWB, CB, CM) and he's a great attitude about him and suspect wouldn't complain about a squad role.
Anyway I still expect he'll be out the door by the end of the summer sadly.