Current major source countries of immigrants (Mexico, Vietnam, China, Turkey, etc) are going through steep birth rate drops. The vast majority of countries with

Current major source countries of immigrants (Mexico, Vietnam, China, Turkey, etc) are going through steep birth rate drops. The vast majority of countries with birth rates high enough to maintain their own population while allowing for waves of immigrants large enough to sustain other countries are in Africa. And they're dropping. Assuming the rates keep going as they are, in about 50 years, we'll be down to about 10 countries that will have enough people to migrate to other countries to support their economic ponzi schemes/social security, and the world will just be too big and full of old folks to get by with so few immigrants. Before we get to that point, we need to start working out economic systems that don't rely on constant growth to be sustainable.