I've said it before, feats do not always = strength. Killer had a decent showcase on the Rooftop, shown capable of harming Kaido yet now his main fight will be with Hawkins. Zoro's feats on the Rooftop were amazing, agreed, but they shouldn't be used as an arguement to rule out the possibility of Zoro vs King.
It's pretty clear now with Oda initially setting up the rooftop 5 vs 2 emperors then disbanding them to each have their respective 1v1s or 2v1s, that Oda is not looking to have anymore team fights. Luffy will fight and defeat Kaido, as said by him and
Zoro himself. The fact that Luffy has lost for now means little, as Luffy lost to crocodile twice in alabasta before his eventual win on the third attempt.
Matchups are being setup, with Sanji moving to fight Queen, its highly probable that Oda will follow the pattern he had in Alabasta, or Ennies Lobby and have Zoro and Sanji fight the second and third strongest members of the Beast Pirates which would be King and Queen.
In my opinion, the possiblity in which i see Zoro fighting Kaido again will either be:
1. All the Strawhats come together after their respective 1v1s and have a fight all together against Kaido before Luffy defeats and finishes him, as shown in the anime introduction (which has shown to be accurate a few times).
2. After Kaido is defeated by Luffy, Zoro takes him to the flower capital and cuts off his head with Enma - infront of everyone.