Hmm.. Kenpachi murders all the rest of the Sternritter, but loses to Yhwach. Ichigo jumps in, is beaten to the inch of his life, unlocks loads more of True Potential and kills Yhwach, who, at the last moment, has a brief flashback of his past and at least slightly regrets becoming the monster that he currently is.
Or really, who knows. I just got a major ehhhhh reaction from the implications of Yhwachs game-breaking levels of power. If the letter-powers of the Sternritter are all originally fragments of Yhwachs own power and, upon their deaths, both the power itself and all the power the Sternritter originally had returns in full after he takes a good nights sleep, the limits of his powers are pretty damn ridiculously high. As in, everybody should die the minute he steps to the field with hostile intent.
Overall, Kubo seems to have come up with a character who would be more at home in the Touhou-verse, where everyone is packing the same kind of godlike powers, instead of fighting shounen where said power will eventually be surpassed by the Sayan powerups of the hero and the true power of Nakama.
Edit: @Kaitentsuki. Technically, that already happened. Tia Harribel is the chick. Admittedly, she has only been caught once up to now, but I'm sure this will be corrected sometime next year. I'll be sure to include that in my next, even more incredible plot prediction.