That's at best a temporary situation though. If births are below replacement rate, at some point the population will also drop. People aren't going to age indefinitely.
The blue countries are below replacement rate, and represent most of the world. Green countries are at replacement rate. The rest is above, and are all in Africa except for Afghanistan and Iraq.
https://en.wikipedia.org/wiki/Birth_rate
The blue countries are below replacement rate, and represent most of the world. Green countries are at replacement rate. The rest is above, and are all in Africa except for Afghanistan and Iraq.