Kaido gets an Epiphany and becomes an ally to Joyboy
Someone who ruined wano for 20 years won't suddenly become an ally or will have change of hearts
That would only be true if he didn't have a specific reason to stay in Wano
He definitely has reason to stay in wano because he occupied it for 20 years
Kaido is already accepting defeat at thw hands of joyboy with this chapter. The beast pirates are done with this, you can apply the same logic with King, Queen, Big Mom, Jack, what happens to them then? Especially someone as loyal as King, or Big Mom who saw Kaido as her little brother
You are comparing apple and oranges.
You can defeat calamities.
BM has WCI to return
But kaido has no place nor he can be defeated.
He fought 15 people in a gauntlet while carrying an island all the time.
He is hyped as the strongest with no one capable enough to defeat him.
Even if he loses here then he is still the strongest because Luffy didn't beat him in proper 1 vs 1. So, he has to go down no matter what.
This is also important to save future opponents (BB and others) to get proper hype because as long as kaido is alive they will be number two