But I will say two things:
1) Rome is an example of a great world power that did decline and which did break apart and fall away. This fate could also happen to us.
2) The Classical world of Greece and Rome brought civilization to many places in the world and elevated millions of people. When that Classical world declined and faded, there were long-lasting repercussions. One could argue that the world today is still dealing with the divisions caused by the ends of the Eastern and Western Roman empires.
If America, and the ideals of America, were to fade away, I think it would take a thousand years for humanity to recover from the cultural blow.
At least. If ever.
One enormous difference between Rome and America is American idealism and The American Dream: liberty, justice, and prosperity for all of the people of the world.
Nothing like The American Dream even entered the minds of Rome.
Perversely--Americans who hate the United States, notably the fifth column in the press, Washington, Hollywood, academia, et al., but claim to aspire to universal liberty and justice, and non-Americans who hate the United States and aspire to its destruction, because they consider it an impediment to their ambitions and rising expectations, do so in a misguided and perverse attempt to follow The American Dream.
The great irony is that all of these people would achieve the very objectives to which they claim to aspire if they would embrace the very principles on which the U.S.A. was founded: liberty, justice, and the pursuit of happiness for all people.
These very principles created the greatest, richest, and most just nation the world has ever known. They can do the same for all of the people of the world if they were just wise enough to embrace them.