Right now Luffy seem to be way ahead of every other Supernova, probably competing for a Yonko role.
We might see both Big Mom and Kaido fall after Wano or in the near future. Now what happens when a Yonko gets defeated? Unlike Whitebeard who had allies and territories that were under his protection, Kaido has an army and a country he rules together with Orochi. What will happen to the army after the battle?
I think Eustass Kid might take over, maybe unintentionally inspiring Kaido’s pirates to follow him or something along those lines. Otherwise I don’t see where his character is going aside from following Luffy’s lead, and he is specifically being written as somebody Luffy will compete with in the future, be it a contest or directly…
Now I don’t know about the Big Mom Pirates but I’m pretty sure all these allies Kaido has won’t just disappear out of the story, and I doubt they will join Luffy. Maybe Blackbeard will jump into the frame and take over but I’d rather have Kid gain some leverage…
Kid becoming a Yonko in the future is a highly likely thing to happen considering he is one of the stronger pirates in the same (and next) generation with Luffy and I imagine that he is someone you could consider a “balancing factor” when it comes to power and influence. Although I still see Luffy getting that title sooner than he does, I’m sure they will all get there eventually IF they survive the fall of the current Yonkos they’re trying to dethrone.
Maybe Luffy and Kid will take Kaido’s and Big Mom’s place among the Yonkos at the end of Wano arc.
Then what about Law?
Law is undoubtedly one of the strongest pirates with a truly amazing devil fruit ability BUT I don’t see him getting that Yonko title anytime sooner or even getting it at all. He fits perfectly as Luffy’s ally.
*Theory by jukaa1012