[Potemkin]

The irony of course, is that what happened before to others, can happen in the future to those who were the usurpers of the past.

At the end of the Third Punic War, Carthage was destroyed by a Roman army under the command of Scipio Africanus. In the words of the Roman historian Polybius:

Scipio, when he looked upon the city as it was utterly perishing and in the last throes of its complete destruction, is said to have shed tears and wept openly for his enemies. After being wrapped in thought for long, and realizing that all cities, nations, and authorities must, like men, meet their doom; that this happened to Ilium, once a prosperous city, to the empires of Assyria, Media, and Persia, the greatest of their time, and to Macedonia itself, the brilliance of which was so recent, either deliberately or the verses escaping him, he said:

A day will come when sacred Troy shall perish,
And Priam and his people shall be slain.

And when Polybius speaking with freedom to him, for he was his teacher, asked him what he meant by the words, they say that without any attempt at concealment he named his own country, for which he feared when he reflected on the fate of all things human. Polybius actually heard him and recalls it in his history.

[Frollein]

I would have liked for us to travel to the stars, instead of back into the Middle Ages. That's what liberal degeneracy gets you; Rome fell when the Romans had become soft and flabby.

[Heisenberg]

Let's assume western civilization collapses where all traces of its ethnicity, language, culture, and identity becomes a thing of the past where all that is left is its ruins, art, or records of itself in writing. Germans, Italians, Spaniards, Swedes, Norwegians, Dutch, and English all become a list of long extincted people that no longer exist. The same is for the European people of the Americas or Australian south pacific.

Why are we assuming this?

[Clangeddin]

The assumption is way too far fetched, and soon the technological and AI progress will reach such a level that workers, not matter what conditions they accept, will not be able to compete against the machine.
A human just can't work 24 hours in a row without complaint, a machine can. It just needs fuel/energy and the eventual maintenance when something goes wrong, the moment the cost of the fuel and maintenance per machine falls below the lowest possible wage per hour, it's when you know that shit will hit the fan.
And the "funny" (Well, as dark humour) thing is that the people from the third world country will be the ones at the highest risk of going extinct in that scenario, not us.

[Truth To Power]

Well, only the Brits actually succeeded with wiping out a whole people to the last individual, and not even for the fatherland, but for sports.

No, there are many historical (and obviously, prehistoric) instances of whole peoples being exterminated. IIRC, there was a tribe in South America that were captured and enslaved by the Spanish, and their conditions of life were so horrendous they stopped having sex in order to avoid subjecting any more children to such cruelty. They had no children, and the tribe was extinct within a few decades.

[Frollein]

Source?