After seeing Luffy going basic with his attack/form against Kaido with advance CoC. I believe Zoro gonna behead Kaido(dragon form) with his Ultra Tiger Hunt, but imbued with advance CoC in all of his three swords. ZKK
Zoro will presumably be the one to kill Kaido. Luffy never killed characters advertently, and Oda has been portraying Kaido's words "perfection can only be found with death" probably for a reason in that so specific, and also Zoro's specific declaration himself. And all those experiments Kaido conducted on his own body. Put all elements together.
Luffy declaring "I got this" was presumably a circumstantial matter linked to Zoro's poor physical conditions. He would most likely not have spelled those had Zoro stood substantially healthier.
If Kaido manages to resist Luffy's assault enough time before Zoro returns to the battlefield to check what's occurring (cause he presumably would) and/or Big Mom helps Kaido out, we could most likely see this coming to fruition at long last.
The scenario where Kaido is defeated and only later Zoro still cuts his head off strikes as less likely for me now, but that also has to be accounted.
i really see it like this , all the strawhats / alliance done with their fights , unaware of the fight result between luffy and kaido. luffy and kaido fight climaxes, maybe 5 gear , or just luffy with advanced conqueror and luffy manages to give his all out attack and take down kaido. then luffy suffers from his power drawback as always..and here unexpectedly kaido all beaten up barely manages to stand up,
pissed that he got to this situation and forces himself to do a last attack on luffy even though he could barely moves.. and just before his hit conncets, zoro comes and blocks the attack. then zoro says fuck it, risk it all and let ennma sucks all his vitality/power ( cause we know he will risk it all for luffy ) and deals the finishing blow to kaido and drops on the floor dried up.. (think aboout it same way as the kuma situation ) and nobody will ever know what happened. this is the only scenario where i see zoro killing kaido.
i am 100% for ZKK , it will be really hype but jokes aside if it happens it will be zoro and friends, we are at the point where luffy needs to win vs kaido so he could be at zoro lvl, it's funny if you think about it, luffy getting knocked up again and again, and we have zoro taking full blow from kaido and big mom and still standing, and then cutting kaido.Some guys seems to forget luffy is a DF user, gomu gomu no less, thats why we dont ever talk about injury or broken bones with him, people tends to underrate zoro achievements with all those injurys. it is just sadly luffy is the mc of one piece. i dont ever see oda giving zoro more limelight than luffy at the end. it really wont make sence. thats why there needs to be a plot where it makes sence.
The issue with Zoro killing Kaido is that he has really been presented as unimportant in the last few chapters and spotlight has been put on Luffy, Law and Kidd.
Oda hasn't created any personal conflict between Kaido and Zoro, he hasn't created any family ties with Zoro and Wano Kuni where he could have written revenge archetype with Zoro killing Kaido.
Before Odens flashback there was one plot point supporting Zoro damaging or even killing Kaido and that was Enma supposedly being the only sword to damage Kaido but that was quickly proven false in the flash back.
At this point all we have is loose parallels of Ryuma slaying the dragon to save Wano Kuni from it but issue with that is Zoro has even lost Shushui and so far Oda hasn't put any focus of Ryuma besides those words from Gyukimaru
And now we are in the starting point of the war, the strawhats are in Onigashima and next step is the plan coming into fruition.
The only plus point in Zoro killing Kaido is his sub plot with Hiyori but even in that sub plot Orochi was portrayed as main antagonist and not Kaido.
I can definitely see Zoro beheading Kaido.
He will definitely recreate the legend of slaying a dragon.
There is also an interesting comment that was made when Hiyori stated she would give Zoro enma in exchange for Shusui.
The comment was inherited will. We know Oden wanted to defeat Kaido and open the wano borders.
That is extra foreshadowing
They would rather come up with a nonsensical theory about Moria killing Kaido and appeal to ignorance rather than look at the very obvious foreshadowing and buildup infront of them that Zoro will be the one to carry it out. It's just bias against Zoro and denial at this point.