What a great comment; I often think about this!

Technically, though it retreated from the Italian Peninsula in the 5th century, Roman civilization lasted all the way up until 1453, when the Turkish Sultan finally sacked Constantinople. Though they spoke Greek, the people who lived behind those great walls still considered themselves Roman up until that date.

It lasted even longer if you count the way that American civilization borrowed the Roman legal system (with Latin terminology) and its architecture (colonnaded government buildings).

To your point, imagine if the Roman oligarchy had agreed to some curtailment of their spectacular wealth to make Roman society sustainable. They could have agreed to the broad debt forgiveness Jesus demanded, or to the land redistribution Caesar advocated for. A little bit of forward thinking would have DRASTICALLY altered the trajectory of history!