For the liberal, former White Western nations are just abstractions, not based around a particular ethno-racial group. Thus, there is thus no problem replacing Whites with migrants from anywhere, as all people are interchangeable. This ideology emerged after a sustained academic war against the concept of race, to discredit the vast amount of empirical evidence that had been accumulated. However, despite this, some brave race researchers have pressed on and still shown that race matters, and hence that vast mass migration of non-Whites will lead to a modern Fall of Rome situation.
Such are the academic studies, but the US will find out first-hand the reality of race differences, as the country is fast becoming majority non-White. The immediate political consequence will be that the Democrats will become a total dictatorship, with no more need to engage in electoral fraud to defeat the likes of Donald Trump. A new report has shown that almost 50 million people now living in the US were born in a different country. No nation has ever held together with such swelling diversity. The fall of America will leave the West, especially Australia, open to total destruction by the same globalist forces acting in other countries throughout the West. Call it the Great Historical Payback for allowing migration in the first place, and going the path of White deracination.