This is an insane theory that took a ton of research and questioning, but after days of arguing with myself, I genuinely cannot think of anybody on Wano other than Zoro & Kidd who can finish the job and kill Kaido.. and the fact of the matter is, there is far more buildup and reasoning to suggest that Zoro will be the one who land the final killing blow.
Check it out and let me know how absurd it sounds.. I'm really really sold on this theory.