Precisely why you don't hype something up in a story for 10+ years. Regardless of what happened to Kaido and Big Mom, people would be disappointed.
Eh i feel like we all know who the majority of people that want kaido to get back up and fighting are
The people that want kaido to get up are mainly the same people that don't want luffy to get up. It's less so about kaido or luffy more so people wanting zoro to be the one to defeat an even stronger kaido. Alot of them wanting him to do it in a single attack where everyone in wano can see. That way they can wank zoro and any character semi associated with him
You dont hear luffy fans wanting the fight between them to extend even longer or kid, law, yamato, linlin, sanji, marco, franky, etc. Etc begging for the fight to get extended just so luffy or even their fav can beat kaido
Hell even a majority of kaido fans are happy with everything he's done and shown combat wise. With the ones that want him to get up want it to see how much more they can wank kaido and see him beat even more ass not because they want to see him get defeated again. They want to see him do to wano what madara did to the allied ninjas lol
Kaido dying or not is a totally fine and nornal thing to talk about and theorize cause honestly it could happen imo
The problem is the people that want kaido to keep on fighting dont really care about kaido dying but zoro defeating him and being the hero of wano