I'm sitting in a comfy airchair, drinking tea, and enjoying life while it is still possible. And in spite of all common sense, spending a lot of time and money planting trees and bushes, as I have done since 2010.
It is pretty apparent that we are going to have water problems in the coming decades. You don't need to be a scientist to put those two together.
I am not saying we can't fix it, I do not hold the same outlook as OP. But we will have problems. Even if you don't believe global warming, there is obvious signs of issues popping up with water, and heat. Mexico, parts of USA, Canada, etc limiting water usage and saying they'll run out if it doesn't rain. That will be a problem.
Short of a nuclear war, I don't think humanity will get close to extinction. But I think we are on a path to lose access to today's cultural knowledge (like microchips, vaccines, aviation). If the population is forced to shrink over the next couple of centuries, wars over fertile ground seem more likely than specialized global supply chains.