GK, CB, Full/Wingbacks and CM is absolutely perfect. Forwards very hard to improve, maybe to some degree with Cavani, Diego Costa or Ibrahimović if Morata leaves, but I wouldn't want neither of them here and they're highly unlikely anyway.
Classic Wingformations like 433 or 4231 would be utter shit, because it would force us to bench or at least play out of position one of our two best players (Pogba in 4231, Dybala in 433).
Cutting 1 of 3 CBs for an additional attacking player behind the striker partnership would maybe improve us (but not necessarily when you look how our 352 was dominating last season). Then again it's hard to find a trequartista thats good enough to improve us definitely. Only sure bet would be James who is completely unrealistic to get.
A real possibility could be someone whos capable of playing some kind of LW/AM hybrid role. Mkhitaryan in this role + CF + Dybala roaming around could turn out awesome. Götze + Mandžukić + Dybala could also be a killer trio.