There is a Trick here
The ones who will Stop Kaido are Nine, not Four
Toki's Prophecy won't change
So how does Momotaro's Story fits with Nine?
It's simple, there are Two Momotaro Stories + Kaido Slayer
Momo isn't only Momotaro in Wano, O-Tama is Second
Hiyori isn't only Bird in Wano, Marco is Second
Yamato isn't only Dog in Wano, Onimaru is Second
Luffy is currently only Monkey in Wano, but trust me, Second Monkey is coming soon
So it's Two Momotaro Groups, making 8 Shadows
And Zoro is Ninth Shadow
And Oda have been hinting at this for so long
Two Birds in that Wano Alliance Drawing
Two Oden Children
Two Kid Characters (Momo & O-Tama)
Oden's Two Swords
Ushimaru & Zoro
Sanji & King
Inu & Neko
Kiku & Izou
Two Odens (Momo)
Two Tokis (Hiyori)
The Title of Chapter 1023 literally summarized everything "Two Peas in a Pod"
There is "Two" of everything, Wano is literally a Mirror
Oda isn't trying to hide Momotaro's Story, but his own Addition is that he copied it & made Two Version of it
To create 8 Shadows & finally add Zoro as Last Shadow
At this point, I don't see how ZKK is happening. Zoro has his hands full with King. Let's see Zoro actually do some damage to King first.
Also Momotaro. The battle against Kaido is based on Momotaro. The final battle will feature Momonosuke, Luffy, Yamato, and Hiyori against Kaido (who represent the characters Momotaro, Monkey, Dog, and Pheasant respectively)
Oda did nothing but portraying the theme of Kaido's death involving Zoro the most due his declarations and the notion no one else of the Big characters apparently displayed the balls to kill Kaido off other than Zoro for now. He also wields the right power so. So many elements are pointing at the Grandmaster haha.