Kuszczak is cert to leave IMO. Owen and Berbatov look increasingly likely to leave too, and I wouldn't be surprised seeing the back of Park (opens up a spot for another winger). de Laet is a goner too.
So, including Ben Amos who was born in 1990 (not sure whether he'll stay due to registering reasons) we'll have 22 spots occupied within the first team which leaves room for improvement.
GK: No one needed
RB: Rafael, Jones, Smalling
LB: Evra, Fabio, Fryers
CB: Vidic, Ferdinand, Evans, Smalling Jones
We could do with another defender, preferably a centre- or right-back. Or maybe we'll just use someone like Thorpe or Veseli at the back.
CM: Carrick, Cleverley, Anderson, Scholes, Giggs (Fletcher), Tunnicliffe, Petrucci
Can't see us buying a central midfielder.
LW/RW: Nani, Valencia, Young (Giggs), Brady (?)
In case Park leaves the club a fourth winger is required. Do not want to see us play Giggs out wide too often, leaves too much space exposed as he usually comes inside quite a lot. The Gaitan story gained a lot of legs a couple of months ago so don't be surprised if the interest is genuine.
ST: Rooney, Welbeck, Hernandez, Macheda
With so many attacking options in midfield Fergie might gamble and take these four players as our striking options. We hardly used Owen and Berbatov this year, so Macheda being fourth choice won't hinder our campaign IMO (and there is still Will Keane).
So... I expect another winger to come in, maybe a defender, but taking our wage bill into account I would be VERY surprised if there will be more than one big signing.