Nostalgia and historical bias playing a part in here where people are saying Rose is better. We can't be sure of that anymore. Rose and Davis are different kind of players, but considering how long Rose has been out for, I would be shocked if he manages to get anywhere near his prime over two seasons ago.
Shame, but Rose would not be able to replace Davis this season as first choice and probably will fuck off to City in January. But silver lining is, Davis has advanced to a level above his best over last season.
The key thing is, doesn't matter if Rose plays or Davis plays, under Pochetino's system and tactics, fullbacks are always going to look extra special and Rose will be replaced by someone who will grow into a great fullback for us.