Many people think that Zoro is done after the defeat of King in Chapter 1035. That he has no important role (at least not a combat one) to play for the remainder of the arc.
I think the opinion is misguided. Zoro still has two very important plotlines that have yet to receive any sort of resolution in this arc.
Oden and Enma
Kaido repeatedly drew a connection between Zoro, Enma and Oden.
That connection has yet to have any payoff to date. If Zoro is done for after the King defeat, then pray tell, what was the purpose of these scenes?
Even at the end of the King fight, Zoro still had not yet reached Oden’s mastery of Enma. He says that fighting with Enma fully unleashed would kill him.
Meanwhile, Oden could wield Enma as if it were as light as a feather.
However, Zoro has been setup to surpass Oden’s mastery of Enma. To accomplish that which Oden could not do.
This still has no payoff yet.
Finally, Kaido’s declaration that there shall never be a “monster samurai” of the likes of Kozuki Oden has still not been proven wrong:
Kaido needs to eat those words and acknowledge that such a samurai has been born.
This leads me to expect a second confrontation between Zoro and Kaido.
Zoro has a storyline involving Ryuma and the people have Wano that has still not yet met its conclusion.
When Zoro first came to Wano, he was scorned as a murderer and grave robber.