There is a difference between an empire's collapse and a nation's collapse. Most of the colonial empires of the past are now collapsed, and yet the countries remain. So many in Europe were empires, and the UK pretends its commonwealth as the global geopolitics changes.
I suspect there is a solid nation -- ours -- with a solid Constitution, and a frail, doddering and now angry "empire" which is the MIC and deep state bureaucracy, fighting for relevance all the while screwing over ordinary Americans at an increasing rate.
Here on FR so many are still aligned to the "empire" for reasons of their own, and will become all the more angry as time passes. My wife and I are fully confident that the Constitutional "these United States" will survive, for having seen first hand the aftermath of another empire or two having died, i.e. the USSR and specifically the DDR. Our once East German friends testify that an "empire" can die and a nation live on.
Persevere.
I am far more cynical than you. The geography of America will always exist, as do the outlines of nations in Europe, but the internal mix of populations has become poison. The constitution has no meaning to our new arrivals, and as long as they will work for bread and lodging, aging whites will willingly stand at the back of the line to live one more day.