Byzantium was in decline for seven centuries until the Ottomans pulled the plug. Rome was in decline for several centuries prior to its sacking.
Climate change and the accompanying plagues, droughts, famines, and calamities that accompany it might accelerate and exacerbate the state's capacity and willingness to respond to these crises, but all it might mean is that this is a new normal added to the reproleterization of American life.
I don't really have a point but it is just a thought that I (perhaps others) are going to have to accept that future, and that is a kind of new world I am unsure as to how to adapt to.
I think the US government is going to stay where it is. The 2nd Amendment has ironically made revolution much harder and more violent for the proletariat. It seems the people who most want to buy guns and use them on other people actually side with the tyrannical government in order to legally kill protestors, revolutionaries, rioters, terrorists, whatever word you prefer.
Now there's a layer of militias an prole revolution must fight through before it even gets to the first layer most other revolutions face first, the militarized police, and beyond that the military before finally reaching the political elite.
I don't think the left is strong enough to defeat that combined force, so I don't think the USA will fall to revolution, at least not a typical one. It's either long, slow decline if fascism is politically defeated, or, if the rising fascism that Trump's politics represent wins out, the USA will become a global supervillain of comic book proportions and will need to be defeated militarily as it reenacts the Iraq War on some other country, second time as farce.
And since I'm way off into speculation land, let me predict who would probably join a coalition against the USA that could beat the USA. I think the combined forces from Turkey, China, and Russia would be likely partners to beat the USA, who would probably ally with Japan and probably some European fascist states like Poland.
So my plan is to just move. To where, I don't know yet. I'm trying to figure out what won't be an absolute hellhole in 50 years that I can also afford to move to and live in.
I don’t disagree with your general point, but keep in mind there’s often been right wing militias for left revolutionaries to contend with as well as the bourgeois state (this was the case in the Russian rev for example).