Oda is kinda wrapping this arc up in a rather unconventional way. Usually an arc reaches its climax with a notion of ambiguity; the Commanders are defeated but the main anatagonist is still looking like he is going to win, or is at least ignorant towards his eventual defeat, while there is still a sense of uncertainty.
Crocodile for example lost his organisation and power, but he still found the Poneglyph that he was looking for before getting his ass kicked and he was certain that he wont lose until the end. Right now, Kaido is very well aware that he already lost. Even if he manages to kill Luffy, everything that he has build up is destroyed. His smile factories, his army, his kingdom, his alliances with Doffy and Big Mom and most importantly his reputation. Kaido is already politically defeated and he knows this. And he knows that he might not make it through his fight with luffy.
The last panel indicates this: He is looking at Luffy like: “Alright this might be it”. It’s not a “this is fun I love raw fights”-look, it’s not a “I’m about to kill ya”-look. It’s a nostalgic, kind of melanchonic smirk.
Yamato’s words that Onigashima is about to fall in that panel underlines this. Not only is Onigashima about to fall, but so is Yonko Kaido the King of the Beasts. Yamato’s statement fits perfectly to Kaido’s smirk. Unlike all other antagonists who where ignorant and kind of bitter towards the end, he accepted his eventual downfall. That’s what makes Kaido stand out as a main villian and all of this meta-dialogue is showing us what Kaido is like. Kaido doesn’t need a flashback, we already know Kaido’s soul through his actions and the meta-dialogue that Oda implements perfectly. Oda is really a master of subliminal meta-communication and indirect storytelling.
So this fight is different from previous fights. It is the opposite to the fight against Katakuri. There is no real tension; we already know everyone is safe before Luffy has even beat the antagonist (Raizo’s masterplan).
The narrative is that Kaido can’t be beaten with one master-technique or ultimate punch, he needs to be dragged down with everything you got. They have been dragging Kaido down since Punk Hazard. So when Kaido falls, it’s not only because Luffy punches him really hard, but it’s because of all that they have been doing since Punk Hazard that has led up to this point. Kaido is aware of this; the part where he says that he has lost a lot underlines this. He is not ignorant, he is very well aware of the development that led to this. He is very well aware that Luffy is not just a reckless rookie. This makes Kaido stand out from all other villians. Kaido is one of the most intelligent villians so far.
All of this shows that Kaido is, at least to me, an outstanding antagonist and very well written character and this fight, even if the climax is written kinda unconventionally, is the most interesting one so far.