Right now Luffy seem to be way ahead of every other Supernova, the only one able to stand up to an Emperor alone.
Now that Kaido and Big Mom have both been defeated, what happens? Luffy is already considered the fifth emperor so we can assume that he will take Kaido’s place as a Yonko. But who will take Big Mom’s place as a Yonko?
Unlike Whitebeard who had allies and territories that were under his protection, Kaido has an army and a country that is destined to return under the guidance of the Kozuki Clan. So what will happen to his 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 strongest 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.
Then what about Trafalgar 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