"This is precisely the trajectory of American degeneration, consummated soon in their ejection from global top slot."
World Empire is very expensive. The Empire is forfeit when Imperial policy, in contradiction to sound leadership, inevitably destroys the central economy. What cannot be bought will not be bought.
Countries can afford Empire in the first place due to superior economic policies. Not that they're [good] policies, exactly, but rather that other countries are even worse. Either from raw stupidity or from complicated stupidity in the form of trying to copy late-Empire policies before even having an Empire.
On the plus side Communism is highly educational. If enough peasants learn about the intense badness of Imperial economic policy, it might even stick for more than a generation. They still remember the year of five emperors and vaguely grasp why Tarquin wasn't cool. Hungarians might, in the future, understand that an open immigration policy is just cause to declare war on the central government. "Flagrant betrayal" is putting is politely.