I've been thinking for a while that the rooftop battle isn't nearly the end of the fight. Something happens and the battle shifts on mainland Wano.
Basically, Hybrid Kaido breaks Sandai, which gives Zoro a great reason to get Nidai (especially due to the interest he had in it in the beginning of the arc) from Tengu.
Not only this, if that 10th person really is the person from 982, who has a similar kimono to the person talking to Crocus 350 chapters ago, and also happens to be Shimtsuki Kozaburo (returning to Wano for x reason), then he can explain Zoro's Shimotsuki Lineage. Nobody else really can in Wano because they don't know Zoro.
Its a stretch, but this could be a decent way to do all of this for the character.