[Retric]

People dying of heat in the US tend to have other serious medical conditions so it’s unlikely to change overall life expectancy significantly.

Also, peoples homes have been redesigned for AC. The most obvious being people used to sleep on upper story “Sleeping Porch” in the summers. Those living spaces have almost universally had walls added. There’s many more subtle architectural changes that have gone away such as ventilation above doors, setting homes up for cross ventilation etc. Most of which simple doesn’t make sense in a world with cheap AC.

https://en.wikipedia.org/wiki/Sleeping_porch / https://en.wikipedia.org/wiki/Arizona_room etc