[hinckley buzzard]

The motive force behind depopulation is and will be a secular hedonism made possible by material prosperity. The elites won't have to do a thing, the human race is already doing it to themselves. Western Europe, the US, Japan, and many other countries at or approaching ZPG will continue to see native populations fall. Spreading prosperity will see the drive for mass emigrations fall across the globe. How this will ultimately affect economies is undetermined, given the process of ongoing innovation and adaptation.

[RayChuang88]

Interestingly, both the Left and Right politically are talking about this for the past few decades. Even Alvin Toffler from The Third Wave on note that advancing technology will dramatically reduce the pressure to raise a lot of children, and that could result in a "demographic cliff" that by 2100 could cut the human population down to 4.5 to 5 billion people. I read Harry Dent's book The Demographic Cliff and the developed countries are only the first to see that drastic human population change.