A swap deal with Aguero (don't think Guardiola fancies him) would be OK with me. I prefer it to forcing him to see out his contract because I don't trust us to go out and replace him with a player of his or Aguero's calibre. We'd just have to tweak our formation a bit with Ozil operating behind Laca and Aguero.
I know Aguero's stock has fallen a bit but he's still a guaranteed 30 goals a season striker. I don't think we'll be really worse off with him in place of Sanchez.