From the look of it, I don't think human extinction will happen quite yet because at the current stage, human population is just so huge!
Even if there is a massive natural disaster, or a big health epidemic disease, it is quite impossible to wipe out the whole human population entirely because we are very scattered around the world. We have humans in the cities, in the jungles, at the ice poles, at the dessert, living on the sea etc. We are almost every where!
But what would happen if we are all gone?
