The same phenomena is playing out throughout the developed world and even in much of the developing world, though. Europe has even lower birthrates than the U.S, China had a huge baby boom in the 50s and 60s followed by a huge baby bust in the 80s under the One Child Only policy, and Japan has been in this situation since the 90s.

What would reverse this, internationally, is if the high-youth countries of Latin America, the Middle East, sub-Saharan Africa, and rural India could be rapidly integrated into the global economy. There are large political, cultural, and educational barriers to this, though.