If I know anything about van Gaal, then he certainly won't give a damn about Rooney's contract situation; van Gaal has never been afraid like that, and he is one stubborn dude. You can bet your house that Rooney will either play where van Gaal wants him to, or not at all. Either way, I'd say a proper manager can create a good front line with RvP, Rooney, Januzaj, Kagawa, Mata, Young, Nani, Welbeck, Valencia and Hernandez.
Not that he is any good, but Evra has signed a one year extension. Means they have one less position to worry about, and Rafael is a good player on the other flank. As for Carrick and Fellatio, I don't think they are one bit worse than Arteta and Flamini. In a proper midfield they certainly have a role to play, but I reckon Man U needs two class midfielders. In Jones, Smalling and Evans I think Man U has 3 competent CBs, but they need a top class one to really run that defense.
All in all, I'd say Man U needs 2 CMs and a CB as a minimum. The right players there and I think that may be enough to be right up there with the squad they have. If you add a Luke Shaw to that, then things get really interesting IMO. As a bare minimum, that doesn't look insurmountable in one summer. In fact, I think we have just as much to get done this summer.