We are an Empire, and I'd argue that minus our role in WWI and WWII, saying "great" depends on what you mean by the word.
The thing is, as a Representative Democracy (let's avoid the nonsensical, "it's a democracy", "no, it's a republic" stuff) we citizens can vote in people who are less god-awful terrible than their opponents. The goal being to wind down the Empire part without the maniacs getting the levers of power and using nuclear weapons and drone terrorism to extract "revenge" or to plunder before the Empire crashes into the ground.
In fact, I believe that we don't have to crash - we can set this fucker down gently enough so that US citizens and the world-at-large doesn't need any additional suffering. It won't be particularly comfortable or pretty, but it can be relatively peaceful and non-destructive.
But it takes a lot of money, time, and willpower to prevent maniacs from taking power, because at the end of the day, it's natural for a maniac to seek power, whereas it's unnatural for decent people to seek power...hence why politics is almost always an uphill struggle between decent people and fucking maniacs.
So, yes, Empire is going to come to a halt, as it should. But we don't have to let the maniacs control it and drive it straight down into the ground (to continue using a failing aircraft - a B52 would be fitting - as a metaphor).
Let's put this thing down gently and rebuild internally. To do that, we have to continue working to prevent the maniacs from intentionally crashing.