User blog comment:Xilinoc/Ch. 669 - 刃 II/@comment-7606564-20160410222156

So.... On a scale of 1 (ichigo showing off his new bankai) to 10 (hanataro whipping out a bankai)... How impossible is it for Unohana to come to life and pull zaraki out of his Oni state. I'm really hoping he can't control it. His mind is just flat out gone and he would start attack byakuya or something.

So going off this assumption someone needs to pull him out of it. My guess is either Shinji bankai, or perhaps Unohana returns and we get a bit more of explaination on Minazuki (name meant the final act right?).