Where would this take place? In places where the wet bulb temperature is already getting close to the limits of human endurance:

https://www.theguardian.com/science/2022/jul/31/why-you-need...

People can survive amazingly hot temperatures, as long as they can sweat - once the wet bulb temp gets far above 31c people are in trouble - the theoretical maximum is 35c.

We won't hit these wet bulb temps in places like the US or even much of Europe, but built up China, India etc are at risk of approaching these in our lifetimes, potentially far sooner.