but that's what I imagine US Empire will look like in a few hundred years.

I can never take anyone seriously who talks about any of the current geopolitical entities still existing in "hundreds" of years, let alone the already-in-early-collapse US empire specifically. As others have said, collapse is (more often than not) a process, but that process can happen extremely rapidly if the medium it exists in allows for it or even demands it. That medium is global society and it is a vastly different kind of entity now than it was a century ago, even more different than it was before the industrial revolution, and barely comparable to it was around the time the Roman Empire that often erroneously gets used as a metric of comparison. Sometimes people like to refer to how it took more than a century for it, or some of a number of older empires to fall, but they aren't accounting for how different the material conditions are now, such as the conditions that allow for information to travel instantaneously to opposite ends of the globe (to name one obvious example) and how significantly these differences inevitably increase the rate of societal and political change.

The rates of technological, social, and environmental change are all increasing, and not just as a linear increase, it's exponential. By the turn of the next century the world will be entirely unrecognizable from what it is today. Climate change alone will ensure that, with mass migrations (and die-offs) happening on a scale humanity has never seen. That much is unavoidable. It's insane to think the US will still exist in a few hundred years. The face of the planet even, in terms of the biosphere, will be completely different as a result of the ecological collapse wrought by climate change, and some people here think the current unstable political entities will survive that? It never ceases to surprise me when communists, ostensibly with an understanding of historical materialism, fail to get this.

edit: I don't mean to go off on you in particular, keepcarrot, I generally really like your comments. This is just something that bugs me when I see it come up here, in part because it makes me feel like even my fellow comrades don't understand how dire things are now in a way that they weren't in the past and on a scale that wasn't even registered in the past.