A friend made an interesting point on how the narrator for some reason specifies the fact that it was a sky battle between Luffy and Kaido. Kaido is known as the strongest on land, sea, or air; so maybe there’s two more quicker battle that need to happen?
It's not an interesting point whatsoever.
The narrator has always specified the location of each fight (battle of livefloor, battle of skulldome ...) in this case Luffy and Kaido were literally fighting in the sky when the clash happened
Wanna know what's an interesting point?
This is the first time the narrator calls a battle "decisive" which means there won't be another one lol.