It would be pretty epic if she killed Zaraki, too bad it won't happen.
After the soul society arc, Kubo hasn't been quite as good with plot twists(if you could see one come out of that situation).
To answer Tsuneo on the prior page, Zaraki had that scar before he joined soul society so they would have to have met a long time ago which falls into making sense when he named little Yachiru when he first did since he had the scar then.
However the fight pans out I'm feeling that it'll be freudian, not sure why it just feels that way. A man and a woman connected by the scars they gave each other, considered vile creatures and criminals by the society they protect, also considering the amount of space they give each other on preferring NOT TO fight(that filler in the zanpaktou rebellion scene was funny), AND the mutual hatred and implied respect for each other?
Sounds like a lot of sexual tension but I could be perverted and wrong.
(Or both)