There's no doubt in my mind if someone like Wilshere, Busquets or Schweinsteiger were to become available, we'd go all out to sign them and considering what we were willing to pay for Lucas and Hazard, the money wouldn't be an issue.
Beneath that level there are players who have shown that they could've contributed to our squad like Cabaye, Dembele and Witsel. It's easy now to say that we should've signed these players, but the problem is, not one of them could've guaranteed that they'd be successful and would probably be on decent wages which makes them hard to sell (ask City). Every season a couple of players have a great year and get linked to bigger clubs, like Charlie Adam, Peter Odemwingie and Obafemi Martins. More often than not, they are footballs equivalent of the one hit wonder and never reach that level again. While our midfield may not be the strongest, at least Sir Alex knows what he'll get from Carrick, Scholes, Giggs and Fletcher, all the while he can develop Cleverley, Anderson, Powell and Academy players.
Perhaps this is why we haven't made the midfield signing everyones wanted in the last few seasons, but going into next season, theres a very real chance we'd actually be short on midfield options and I do think we'll make midfield signings this summer.