Even Frimpong might be fit by then. Also if we have Wilshere back by then, a deep-lying midfield two of Arteta and Wilshere is not bad.
I agree, Arteta was great in the DM role last season, put him next to some one who actually chases back as well, like WIlshere, and he will be even stronger because he's getting support. But I think that would be an option should we not sign a new DM. Which then leaves Song to play as our attacking midfielder, which isn't suitable. It could explain why we are supposedly in the market for a new playmaker supposedly. Maybe this is a back up plan if we don't get our 1st target.
...and M'Villa had the MOST successful passes in the French League. M'Vila is MUCH better than most people realise - he's going to be TOP TOP class. Saying that I still rate Song very highly.
Song is a utility player. We need a proper DM to patrol the space in front of the back 4. Song would still get plenty of games in the various midfield or even centre-back positions.