IMO these nut jobs aren't really saying anything novel, just obvious stuff in alarmist tones.

Generational churn makes him right in a way.

The olds will die and policy will change.

Google examples of Olde English. We don't write and talk like that. That English Empire "collapsed" in that its population vanished.

The alarmism is unhinged because, well, yeah. That's how it goes. Will they call themselves Chinese or whatever still? Who knows!