Actually, it led to the collapse of major city states, but they were never "wiped out." In truth, power shifted from the south, to the north, to the middle regions over the course of centuries and millennia. We only think Mayan civilization "collapsed" because of our Eurocentric bias and the fact that we didn't know about the abandoned cities the 19th century and after.

And no more civilization has ever disappeared. We see the Roman Empire by its enduring presence in the Romance countries (France, Spain, Italy), the Mongol Empire lived on in countless empires that spanned East to Central Asia, and the Ottoman Empire's influence can still be seen across the Levant. The movement of people, the influence of trade and culture, and language all are a testament to what came before.

Then again, all this feels like bloody nitpicking considering I agree with you wholeheartedly about the central message here. Environmental collapse is what led to the breakup and dissolution of countless empires and dynasties throughout history.

And yes, this is precisely what is happening right now on a global scale! People will inevitably migrate, centralized authority will fall, and humanity may very well carry on. But considering that the issue is global, the collapse is likely to be much more severe than in previous instances.