I don’t have a cristal ball to refute your answer but I have my knowledge about history and biology to disagree: life in earth has to main goals: survive and reproduce. There’re many species nowadays adapted to what most people consider extreme heat: from elephants to lions, hienas, giraffes, humans, many species of trees and bushes, etc. They will just survive by simply moving their migration routes somewhere else (plants and herbivores would start the shift, predators would follow them).

Humans are extremely adaptable, as you may see if you look at how there’s human life everywhere on the planet. We would need to adapt, for sure, but we as species will survive. That doesn’t mean it will be simple, but we will. Many years ago an expert said on a documentary (can’t remember, sorry) that the next world war would be centered about water control. I agree.