In 753 BCE, The city of Rome was founded. By the 1st Century CE Rome was the most powerful trading and industrial power in the Western World.
Only two hundred years later, in 330 CE, the Roman Empire divided itself into both Eastern and Western capitals, Rome and the new city of Constantinople on the banks of The Bospherus.
For the next hundred years, Western Rome suffered attack after attack by barbarian forces until, in 476 CE, the city of Rome finally fell to them.
However, Rome in The East, centered at Constantinople prospered and thrived for many centuries afterword, still being one of the world's richest and most opulent cities 600 years later when European Crusaders passed through on the way to conquer Jerusalem for The Pope.
In 1453, Eastern Rome and the city of Constantinople fell to The Ottoman Turks ending a contiguous existence of over 2,000 years.
America has changed much in it's short 200+ year history. We've grown from a relatively small consortium of colonies into giant superpower and economic powerhouse for the world. Our economy has transitioned from agrarian, to industrial, to service industries, each time with great success.
Just as citizens of early Rome would have no doubt felt the Rome of their grandchildren was very different from the Rome of their fathers, so the America of tomorrow will be almost unrecognizable to us today.
Change is inevitable and it's pace increases with each passing year. However, it will continue to be America.