Do you expect the other Supernova to be defeated?
How do you figure Big Mom plays into this? She also wants to kill Luffy, and Luffy has preexisting conflicts with her.Wano is not like Alabasta or Dressrosa with one sole clear antagonist. I'm not sure how well the story can accommodate a dedicated 1 vs 1 between Luffy and Kaido to resolve things.
Furthermore, for this battle specifically, the narrative is about the Supernova beating the Yonkou, not just Luffy defeating Kaido. That's not the prophecy being prescribed.
And i believe that figure is supposed to be the reincarnation of Joyboy who happens to be Luffy: https://worstgen.alwaysdata.net/for...ncient-weapons-and-the-world-government.2029/
Who is carrying the burden of Oden and his scabbards, and attempting to accomplish Ace's will in his stead
It was also the purpose of Yamato saying it was fate that brought Luffy here while highlighting the significance of the D word in his name
Who also originally thought Ace would be the leader of the group(with it ultimately being Luffy)
And even in the latest chapter, despite Luffy coming out the last, the rest of the SNs didn't move an inch infront of the 2 yonko, with Law only deciding to teleport the scabbards away the moment Luffy request him to
With the moment Luffy comes, he passes by both of the yonko, with Kaido deciding to target Luffy right away, just like the leader of group.
Point then is that, yes the SNs will have their contribution in the fight, just like the prophecy implied, but ultimately the one who'd get the most contribution will be the strongest of them, Joyboy's reincarnation, who will end up beating Kaido in a 1 on 1