best case scenario zoro kills kaido in the final battle of wano. worst case scenario is kaido gets defeated clean by luffy solo, then has the kaido flashback culminating with all the suicide attempts, then its like axe hand morgan getting up to keep fighting with luffy telling zoro to take him down and zoro cuts his head off while a flashback seppuku headsman is swinging his sword down or something. i dont think theres any chance the arc ends without zkk one way or another. kaido as an ally dying to the government is giving him what he wants more than anything, literally "whitebeard did it right" and then he'd get the exact same kind of last stand moment that he fantasized about.
hes either going to lose clean and die in battle while wano is still isolated, in the middle of or over the flower capital, or hes going to suicide by cop (zoro is the cop)