Now, the foreshadowing about Zoro "doing something" versus Kaido is obviously there. And the situation here is that Oda needs to fulfill it in some regard unless he wants Zoro's subplot in Wano to be remembered as the biggest misuse of a Chekhov's gun to ever be seen in a fiction work. When I defend the idea of Zoro fighting King I'm imagining some scenario like the ones you described, in which Zoro performs in a way that fulfills said foreshadowing but doesn't take Luffy's spot in the fight; for example, re-opening Kaido's scar (before going for King) as Kaido himself foreshadowed when commenting on the Scabbards's superficial slash, and/or even striking him with a last hit above Flower Capital just for the sake of symbolism (and in a similar way to Nami versus Absalom, as she gave him the "coup de grace" as he was next to defeat after facing Sanji). In the interim, something would happen that would lead him to King as his main versus. Notice the similarity with Kuma here, since Zoro still performed one of the most remembered moments of this series after everybody was defeated or unable to keep fighting. Imagine Luffy having won, but Kaido tries to wake up with his last breath and, as he's about to attack Luffy, Zoro gives his last effort (even letting Enma drain him for the sake of power in spite of the consequences) and puts Kaido down for good.
As you well said, there are some details that may point at Zoro versus King too, mainly the "second strongest subordinate" trope, the Zoro-Sanji relationship (quite similar to previous duos they've faced in important arcs), King's katana and the whole fire thing (and Zoro knowing how to cut fire, although I'd have rather for him to learn it during said versus). There's also something I've commented in other threads, which is that I simply don't trust Oda's capability to stick to one subplot and wouldn't surprise me he'd try to "put everything" he considered for Zoro, just like happened in other instances of this story. On the other hand, why would we prefer Zoro being a secondary player in the teamfight, outshined by Luffy and maybe even other captains (this I doubt it more), when he can still have a full individual battle with a very strong person and perform one or two big moments against Kaido?