The manga, Scabbards, tell us that Kaido won't be defeated until he's dead. In a q&a section Oda tells us that Luffy won't defeat Kaido but just punching him to death because he doesn't think his fans will be satisfied with that.
Official One Piece sources and information has hinted at Zoro being a second coming of Ryuma and recreating his dragon slaying feat above the capital. Currently in the manga a villain who has a fish DF that just turns him into a dragon is heading towards the capital. We all see where this is going.
Let's keep it real. Look how much Zoro fans have been right about Zoro so far and the arc is not over yet.