but I must admit I've been mentally visiting many of the same scenarios you have, and for many of the same reasons.

Its impossible to predict the future, but it is possible to make informed estimates and educated projections.
I'm afraid I agree with you, only perhaps with less certainty, and perhaps not so quickly. Or as we sometimes say in the stilted jargon of science, "we agree in kind, if not in degree".

I would like to think we can blame this all on Trump, or the Republicans, or the Chinese or the Russians, or the panicky middle classes of America and Western Europe, but I suspect those may not be the causes of the coming emergency, but just the symptoms. The driver behind the coming catastrophe is indeed the climate crisis.

If I were forced to make an actual prediction, I would guess the historical precedent I am most reminded of is the global situation on or about the late 1930s. The only bright spot I can bring up is that if I had been around at that time and place, I would never had anticipated the Axis powers would lose.

So maybe we still have hope.