So, Kaido does not die in spite of all of this. Insane hype for Kaido, the true strongest.
The Oni doesn't get killed
in the Momotaro tale. Oda doesn't have to follow that, lol.
Many things in Wano aren't 1-to-1 at all with the tale.
The simplest example being the whole Kibi Dango story; Tama is the one with that power, not Momonosuke.
Marco and Yamato don't help Momonosuke because of Kibi Dango either, lol.
Obviously, Oda probably got some inspiration from the tale, but he didn't follow it precisely at all.
You have to remember that Kaido is developed as both an Oni
and a dragon.
Will Kaido get killed as an Oni, on Onigashima, by the Momotaro group? No, probably not. They will beat him, though.
Will Kaido get killed as a dragon, in the Flower Capital, by the wielder of Enma (Zoro)? Most likely, yes.
After the 9 shadows v Kaido and the new generation v Kaido, it's now time for the Momotaro group v Kaido.