I think that Unohana, Byakuya and Kenpachi are going to show us what a real badass Ban Kai looks like.. Their un involvement during this fight, means that they are going to play a bigger role later on in the manga.

- and after re-reading this chapter, I hope that Gin will come more into the picture. It could be a " Itachi Uchiha " move ( being double- agent ), but right now without any further evidence; I seriously think that Gin just don't gives a fck about anything and he went with Aizen to HM, just too be free from SS.