I don't expect us to make any major signings in January, therefore, Arteta needs to be bold and either changes formation or trusts Nwaneri to be the man on the right until Saka returns. I believe it will be better for us long-term even if he doesn't have an immediate impact.
Switching to a front 2 with 4 midfielders behind them appeals to me because I trust our midfielders more than I do our forwards. Upfront I'd always go Havertz + 1. The one could be any of Trossard, Martinelli or Jesus depending on form or opposition. I think this is one way to solve our problems up front i.e switching to a formation that requires us to only play 2 forwards at the same time.
Something like this:
-------Trossard----Havertz----
-------------Odegaard
----Rice---Jorginho--Partey-----
Cala----Gabriel---Saliba---Timber
---------------Raya
This drastically changes the way we attack as we'll be using 2 overlapping full backs and Ode has the license to roam which makes it harder for teams to shut him out.
Arteta can also have his box midfield that he so craves by pushing Rice next to Odegaard when we are in possession. Also, generally midfielders are better defensively than attackers, so having more of them could in theory help us defend better.