It will take another 200-300 years for the country to become desolate. Then it will build back up and we get to do it all over again.
And what history book are you reading? What great empire ever came back once it fell? The Medes? Persians? Greeks?
Rome was so powerful that anytime the word "Italian" was whispered, people trembled. Today when the word "Italian" is whispered we think of pizza.
America won't come back. God will simply shift His blessings, through His Son Jesus, elsewhere. Unless of course He decides to bring the whole thing to a close.