Their plan of importing third world replacements doesn't work because the "magic dirt" of western countries doesn't change the minds and behaviors of these third worldians who can't run the systems.
The world population quintupled in the last 150 years. The population explosion and migrations, to fuel global industrial work over the last century and a half, are an unnatural series of events. Expect an adjustment downwards.


Their plan of importing third world replacements doesn’t work
The goal is not no immigration. The goal is good immigration.
How do we identify good immigrants, we do need some.