Ace had to die, for Luffy to train, and Luffy will return the favor for Ace, to defeat Kaido. Luffy carries Ace spirit. He wanted Kaido head bad, and needed a reality check from WB to calm him down. So Ace spirit lives on. So if Luffy had to train for Kaido, then why did zoro want to train? I believe Zoro alwaysed wanted to be the strongest. In his younger day, he had this faith, before Kuina beating his ass. So he decides to train with none other, his rival, Mihawk whos the WSS. Zoro did this, just so Luffy can accomplish his goal in defeating Kaido. Their promise with each other is what you can call the sun and the moon making a deal. Luffy saying he needs nothing less than the WSS, and Zoro claiming I will be the WSS, but if you get in my way of that(make me look bad following u) then we throwing hands. So in short, being bros. lol In pov, Zoro was also training to defeat Kaido too. Zoro(a King) bowed down to Mihawk. That tells me Zoro has willingly accept the burden of being Luffy shadow. Whatever luffy goes, Zoro has his back, and in turn, luffy will get Zoro to accomplish his dream(finding Mihawk for him).
But here the meat and potatoes, Kaido is the strongest.
Whether its with a sword or not, I believe Zoro definition of being the WSS, is to be someone that can cut(defeat) anyone/anything. So isnt Kaido in Zoro way too? Zoro is on Roof Piece, but he failed to defeat Kaido. But here a thing about Zoro, he always vow to redeem himself after not achieving a goal of his. Excluding Kuina; First defeat was Mihawk, then Kuma, now Kaido. Zoro is overdue. Something will happen.
Kaido made it certain that, he won't stop his ways, unless you kill him. Make sense for Kaido, hes the strongest rn, and loves Wano. He needs to die. Theres no other way for Wano to be liberated, other than Kaido dying. Yamato cant defeat Kaido if he somehow makes a return back to Wano (if he doesnt die), and Luffy wont be there to protect them. He not blood lusted like BM, that he will chase the SH to the finale. He ends here. The Gorosei, is afraid of Kaido wrath, so that tells me he wont be a background character if he lives. Nothing or no one can hold him. Now if you understand that Kaido needs to die, Zoro is only one who can do it. Something tells me, Zoro will accept another deal(some unknown to heal him to his peak), just so he and Enma can achieve their goal, to save luffy legacy, and wano.
