If Luffy beats Kaido 1 vs 1 from now, there will be no hype left in One Piece. He will become the most strongest creature in the world and all the lore will be gone.
I really wish that Yonkos will be up there like Meruem in HxH, where no one can beat him unless you need to come up with brilliant strategy or teamwork. It turns out Yonkos are just another Piccolo waiting Luffy to catch up and get beaten.
I also really miss old One Piece where Luffy needs to use brain for fighting (using water against Croc, or try to use weapon against logia). Now, it becomes Saiya's power up with ten levels of Haki. Characters without it become trash automatically. This destroy hype of many characters that have been built up pre-timeskip like Franky. This is sad.