It's aspirational. Empires are bad. Impersonal steamrollers that flatten everything good and interesting about people in the service of production and acquisitiveness. America being over would be lift a tremendous burden we've put on the rest of humanity and maybe offer an opportunity to make the world into something different, better.

As far as your very well-structured categories, that makes it a mix of #1 and #2. This American Empire was born out of two lies: free land, which was actually stolen from Native Americans; and free labor, which was actually stolen from Black people. Those lies didn't just make America. They continue to re-make it every day by establishing a mutually buttressing relationship between that made-up history and our self-image.

But there's got to be an "after" right? I mean, even if you're right that the sentiment is an exaggeration, it is literally the case that nothing lasts forever. Rome was eternal once too. So while history probably doesn't provide the best guess for what post-America is going to look like, it does provide *a* guess - and the simplest one is balkanization.