It seems to me Kenpachi pulled Alucard on Unohana. Alucard impaled Rip van Winkle on the musket and Kenpachi did the same with his blade.
Just look where Kenpachi hand is. Penetrated from her stomach to neck with his sword.
Few things can happen. Unohana can die right there with short explanation of her Bankai. Other outcome is that Kenpachi forces her to keep on living. He won and so her life belongs to him. He can use that to force her to live with him and keep him alive anywhere they go to fight. I would be great if She cut her hair as to mark the death of Yachiru Kenpachi and create new image of Unohana Retsu.
What's better? Zaraki that just killed his mentor and teacher (Think Unohana trained Zaraki when he was kid) or use her to heal any wounds he would sustain so that he can enjoy fighting at 100% forever. Uno x Zaraki double teaming someone would be great. Exchanging blows with him and taking care of each other. Zaraki taking blows for Unohana and her healing him in turn so that they could constantly push forward and attack.
Blondie from VR would be great opponent of Zaraki. I think he was the one that beat him up since Yuha was a fake.