While I agree that Cesc is important right now because we have literally no back-up for Jorginho and that position is so crucial for us, we really should be looking at getting a long-term replacement in.
If Jorginho gets injured for any period of time, we are really screwed. At Napoli, Sarri had Diawara who he had no issues with playing against anyone.
I also agree that it's importance is behind areas that you've mentioned, like our wingers, but it's also going to be a lot cheaper to fix than those positions (so, in theory, easier).