Kira, Hinamori, and Hisagi were probably kept back due to their not having captains to serve under / having very recently worked directly under the traitors-- probably more as a courtesy than as a mark of distrust, though, I'd guess. Still, they might show up to do something badass, too.
Ikkaku vs. Yammy would suck. HANATARO VS. YAMMY. HANATARO VS. YAMMY. KEEP CHANTING IT AND IT WILL HAPPEN.>>12808661
if Hanataro isn't fighting Yammy, then with any luck, what he IS up to is healing Grimmjow so that he can be rewarded with rape. After this, Grimmjow, h4x!revived!Dordonii and Cirucci as well as the afro guy that Unohana healed will join Ichigo's party as the HM version of Kenpachi & Friends' middle-end-of-arc switcheroo.>>12808665
Because of WHAT A TWEEST it would be.
Although they have plenty of reason to hate Aizen & co., they have just as much reason to hate Soul Society.
Granted, pretty much the only person they DON'T have a reason to hate is Urahara, and he's been pretty unabashedly back on SS's team for a while. So right now it slants toward them being on the anti-Aizen team, if not the pro-SS team.