Rome lasted from about 750 BCE right through to 1453 CE, that's a span of 2200 years
You can't use Rome as an example. Technology and the integration of regional economies into a global economy will make the collapse that much faster when it comes. Look at what happened globally the last time.
Will Durant wrote a series of volumes about history, I've only read Caeser and Christ. When you read it you'll see we're going thru nothing new, it's just that we're going thru it in an advanced, technological form.
And when you read even deeper you'll see that basically what we're living thru is a redirection of the focal point of the global economy going back to the East, where it all began. Which makes sense in a consumer economy, as all the population is over there.
A nation of 300 million consumers vs say, China, which has over a billion. If a global businessman with no real allegiance to any particular nation, where would you be looking?
There's money in the building up of a society and big money in tearing that same society back down again. Then you do it all again elsewhere, and everytime you do it you learn a little more about power and how to control the masses. A little more about how to convert organic economic phenomena into controlled economic systems. Decades ago globalism was called internationalism.
The people who are in charge have been at this for quite some time, and have the historical record of thousands of years of history as their guide.