I'm of the mind that this isn't even the final battle.
Luffy and kid and law and the supernova will come up and all get beaten too like The scabbard will be beaten.
OR they will be winning then Big mom burst in an rocks their asses
Then two weeks later we get a round two after some good training and Luffy almost SOLOS Kaido's ass. Emphasis on ALMOST. Some of there will help a bit.
Then Kaido will try to run away. Yes. Kaido said it himself. Pirates run when shit gets tough. So kaido is very fine with running away since he believes thats the pirate way. Then as he runs in DRAGON FORM. Zoro will Behead his ass.
Hehehe.