They could clearly play someone with more dynamism since a midfield three of Iniesta, Xavi and Xabi Alonso is world fucking class.
Villa will rock out with Barca, man. His movement, like Keef said, is awesome. You know he's going to love the space that Messi creates for him and vice versa.
Edit: Or they could Javi Martinez since he offers something going forwards as well as the defensive capabilities that the very limited Busquets does. It's a baffling decision by Del Bosque.