Well the commanders would be the Nakama we know. They'd just be leading lots of small fry pirates with no significance. I don't think a crew with merely 11 to 15 members EOS could stand up to other Yonkou pirate crews.
thats the big problem about the divisions, they would have to lead groups of no name pirates to whom they would be commanders and that would both introduce a lot of straw hat pirates noone would care about and make the bond between the 9 we know less significant, that would be the stupidest thing to do
in Marineford the yonko WB had Marco and he had Jozu and Vista, the rest of WB pirates were fodder except the other commanders and the rest of the pirates there were allies, if the M3o will indeed be able to take on admirals that should be more than enough for a crew of the PK especially with his crew, Franky isnt exactly weak and hes gonna get stronger, same goes for Robin, and all the SHs really, not to mention their allies, there are many already outside the crew who would gladly risk their life to make Luff the PK (like Jinbe or Rayleigh) and that number will only increase, 10 SHs are enough fpr Luffy to be the PK because his power is what Mihawk said at Marineford and I am prepared to bet anything that those same people are gonna do everything in their own power to keep Luffy as the PK if anyone would ever gather enough people to take on the SHs
The main theme in One Piece is the nakamaship between the Straw Hats and if Nami, Usopp, Zoro, Sanji, Franky, Robin, Chopper and Brook would have a crew under them and that would make the friendship between Luffy and each of the other Straw Hats a lot less significant and that would not fit the story at all, it would contradict what Luffy said about what kind of crew he wanted (10) and would oppose the bonds Oda has been showing us now for 16 years
