Bit late to the midfield discussion but here goes.....
I don't see a signing there anytime soon and i don't think we need one. We've got 4 good players for 2 spots and its also likely that Chamberlain will get games in midfield. Don't see what the problem is really. Arteta-Ramsey is good for the moment and we can be fairly certain the plan is a Ramsey-Wilshere combo. Flamini is fine as 4th choice who can be trusted and played when needed.
The only slight question mark is what our best partnership is when Ramsey is missing. Not a fan of Wilshere and Arteta together but maybe go with that in easier games and bring Flamini in for tougher opposition. Flamini-Arteta would probably work a lot better when we have a proper wide player in the side.