Sorry to be a doomer here but I’m convinced that the USA will attempt to at least launch some of its nukes. (Israel already may have used a tactical nuke in Syria; the USA already used nukes when only an insane person would have thought it was necessary.) The guys who work in the nuclear silos are complete lunatics who will launch the nukes without orders—if they sense that it’s over, basically. If the George Floyd protests had really started seizing territory and organizing a revolutionary government, the nukes might have been launched. All the minutemen do is listen to nazis, and all nazis talk about is how every last problem on Earth is China’s fault. We’ll only be safe when China figures out how to disable the nukes (and yes, I know this is extremely difficult but not impossible).

Nukes + total obvious insanity are the difference. No other world empire had nukes when they collapsed and the Soviets were not insane (even though they had definitely lost the plot, let us say).