I'll just talk about the cliffhanger.
Grimmjow wouldn't arrive alone, but I hope he somehow gets in here and tames those bitches for starters. That's his forte. (Maybe their group will arrive? 4 vs 4? Grimmjow, Sado, Orihime, xxx.)
It could also be another 3rd party like the Shiba/Fullbringer team (that could be a 4 vs 4 as well if I recall correctly).
Yachiru...? What could she really do?
Ichigo? I feel it's too early, though I wouldn't mind (that blast did kind of look "white"). It's just that if he shows up now, other characters screentime/impact may be underwhelming.
I say it's either team 1 (I'm always rooting for Grimmjow, regardless of timing) or team 2. Or completely different/unexpected.