I want him to stay because despite how annoying this whole thing is, he's a fantastic player to watch, let alone for United. On his day, he can be unplayable and a bit of a genius. Admittedly, we haven't seen those days much this season, partially because of RVP. I don't really blame him for wanting to leave - before this season, he was a name that would always be on the team sheet, regardless of his performance from the previous match.
I suppose he is replaceable; but I would still prefer it if he stays. With that being said, a part of me just wants him to leave because I don't really want a player at United who aren't 100% committed, same with Nani. It would give Kagawa more chances in his favored position, as well as giving Hernandez and Welbeck more game time.
As long as we sell him abroad, I won't have any complaints. Maybe offer him to Spurs and maybe £10m or so for Bale, but I highly doubt that it'll happen.