United has a chance to match any offer Villarreal accepts for him, and Sir Alex loves him, so who knows? It's not like they will be lacking in transfer funds.
Why would he go to United? To compete with Rooney and/or Berbatov?
I think he should stay @ Villareal for one more season, cement his place in the Azzurri, and then join us (after eliminating the US and England @ the World Cup)