Yeah, Kaido is dying.
He’s a character that is obsessed with death. His introductory chapter is called ”Suicide.” Our first real sight of the man and Oda makes it clear, his aim in life is to die. He talks about Whitebeard “doing it right.”
Cut to Wano and the first chapter is called “Seppuku”- in other words, suicide. There we have the samurai that is meant to assist Zoro in killing himself tell him that it is a man’s death that defines a person. That’s the key theme throughout the arc, and is Kaido’s motivation.
Kaido is the only villain that I can remember, throughout, has so many people talking not about beating him, but killing him. They don’t just want to beat him, they want to behead him, cut him into pieces, cut through his scaly neck, use his head as the prow for a ship, so on, so on.
You’ve got Kaido vs the Scabbards, where he then goes back to the idea of a glorious death, saying how Roger and Whitebeard did it right. He admits that he would have been happy with the Scabbards killing him because it would be a worthy end- interestingly, Kine’mon says dying to Kaido wouldn’t be good enough for him. With Oden’s death Kaido talks about how his death will be talked about for years.
The theme of the Fire Festival is celebrating the dead. The theme of Wano is death, really. Yasu died to ensure the raid could happen. Pedro died to get the Strawhats there. Ashura at the start of the arc is broken because he missed his chance for a meaningful death. The “Snatch” chant is all about giving yourself up and going after your goal until either it’s done or your dead- that’s why Kiku didn’t want Momo saying it. The samurai burnt the ships as a sign of their resolve- they don’t expect to come back.
On a wider level this arc acts as a counterpoint to Marineford, the last time there was such a death focused arc- Ace being all existentialist, Whitebeard essentially saying he’s lived his life and is ready to give himself up for the new era. This is where the second Yonko falls and heralds the beginning of the end, the way the first one heralded the half way point. That means this is an arc where Oda is willing to bend his death rules, the way he did with Marineford.
Also, Kaido’s so powerful that it’s kind of better to kill him off and totally cutting off that plot thread, instead of having him lurking in the wings offscreen the entirety of the final end of the series. BM can get written out with her O-Lin personality, that’s not available to Kaido.
The only question isn’t will Kaido die, the question is will he get the glorious death he wants or an ignominious one where he gets backstabbed by a revitalised Orochi or something pathetic like that. I think it’s more likely to be a cool one, because Oda likes big dramatic set pieces For powerful characters, at least.