After seeing the conclusion of Zoro vs King, I have come to the conclusion that there is no need for ZKK to happen because Zoro vs King fulfills everything that was supposedly promised by ZKK.
- Zoro defeating King is a bigger feat than him merely killing kaido
If ZKK happens, zoro will kill a defeated kaido, likely by cheapshot. This is the truth and there is no way around it. Luffy is the one who is 1v1ing kaido and he is the one who will ultimately defeat kaido. As we know, King is much more durable than kaido. So then why is ZKK such an amazing feat when zoro did an arguably bigger feat when he beat king. And don't get me wrong, I'm not saying beating king is a bigger feat than beating kaido, but zoro isn't defeating kaido, Luffy is. Kaido's neck is less durable than King's body, so why is cutting it such a big deal when zoro already did a better feat?
2. Zoro already gained his Ryuma-paralleling legend by defeating King
King is a lunarian. Lunarians are viewed as gods. Zoro defeated a god, which in turn will lead to zoro becoming known as the "sword god" in wano, just as ryuma. He already slayed a "dragon" above the skies of the flower capital, just as ZKKers said he would for years. What is the point in it happening again, but with a weakened and defeated kaido?
Here's the thing, Zoro just got his big moment. He just got a massive feat and he probably got a legend to his name as well. If ZKK happens, all it will do is take away a similar moment from Luffy. Luffy vs Kaido has been portrayed as a defining part of Luffy's dream. First time Kaido defeated Luffy, "what type of king are you again". Second time Kaido defeated Luffy, "seems like you couldn't be joyboy either". Since Luffy will be PK and will be Joyboy, he needs to defeat Kaido, and it makes no sense for Oda to undermine that defeat after giving the fight such buildup.
Zoro vs King held similar relevancy to zoro's dream. Lunarians are near invincible, moreso than kaido, and Zoro smacked king so hard he took king's wing off. This fight had callbacks to kuina and zoro's childhood. Callbacks to ushimaru and ryuma as well. This is the fight where Zoro tamed enma and mastered ACoC, easily making him one of the top 5 swordsmen in one piece. This fight completed zoro's arc in wano and if you want more from him, you really need to ask yourself if this is something the story needs or if it is something you personally want.