If Kaido does get up, I think Luffy is going to kill him. The giant sword in onigashima is a huge chekov's gun. Since we saw it, fans have been speculating on who would use it.
Also, sorry to tell you this ZKKers, but Luffy doesn't have some sort of moral code against killing. He idolized shanks, who literally had someone get murdered in chapter 1.
You can call it cope, but I think the guy who fought Kaido for the past 50 chapters being the one to kill him holds far more emotional weight than the guy who scarred him once, fought king, and has been KO'd for the past 10 chapters.