Yes, I don't see why we would have to deal in absolutes. When a player leaves you can leave the door open for them to possibly return, but at the same time make sure they're aware there is no guarantee their roster spot would be available if they want to return.
Coaches would still have to look to fill openings, but if player A decides to want to return and you still have both an open scholarship and a need at that position why wouldn't you take them?