I have no way of knowing whether or not Rooney stays, but I do know we'll be sorry if he doesn't (I'm talking about the vast majority, leaving you out of this one Sparky).
We all know he's a very capable player and on his day he's one of the best in the world (apart from the 2 demigods obviously).
Yes, he doesn't seem as happy at the moment, but that's all tied up into 1 thing basicaly. If Rooney was playing regularly he wouldn't have this temper tantrum and we'd see him enjoy his football again, I really believe that.
Now, I'm not saying he had a terrific season, especialy going by his standards, but he was still pretty good.
He hardly ever played in the striker position, spent a lot of time out on the left or dropping deep (or playing as an actual midfielder), and still managed to have the same number of goals and assists as Mata with 7 less games played, someone who the majority claim has had a great season, and his goal/assist to minute ratio this season has been really good as well (pretty sure it was better than Suarez's - another player who had a fantastic season).
And that's Rooney's production in a dissapointing season, and I for one have found no reason to assume Rooney will continue doing a "Torres" for the next couple of seasons.
We don't know exactly what kind of relationship Rooney and Moyes have at the moment, but I don't think it's as bad as some of you make it out to be, or else Moyes wouldn't give a flying feck if Rooney wanted a move, regardless of his talents.
And although they already know eachother, I think everybody on the team from the players to the staff see this as a new challenge, everybody basicaly starts from scratch. This could be a good thing for Rooney, in a way he could use a "reset" button here.
Obviously we'd be able to cope without Rooney, but it would by no means be a good thing or even an irrelevant thing.
Let's not let the fact that we have a strong enough squad (unlike a couple of years ago) cloud our judgments and make us think we'd be "just fine" without Rooney, because we wouldn't be as strong whichever way you try to put it.
Couple that with the fact that the majority of the people at the club want to keep hold of Rooney, and it hardly seems like he's hell bent on leaving, but more or less threw a temper tantrum in regards to playing time, I think there's a pretty realistic chance he'll stay and I've no doubt in my mind he'll improve next season, there's just no way all of this change around the club isn't a factor in regards to "starting from scratch".
In any case, whether it be for United or another team, Rooney's next season will be a noticable improvement over this season's. This was probably as low as his ego/self-confidence can drop, with a new manager and a new system (if he stays) he should improve in both ways (phisicaly and mentaly).