Demographics is mostly booming in underdeveloped countries, with some exceptions. It is likely many of them will follow the same path going forward, and UN predictions expect just that, as far as I remember. For developed countries, the fertility rate typically sits somewhere around 1,5-1,7, significantly below 2,1 required to have a stable population. I could of course cite something like South Korea with 0,8, but that's an obvious outlier. It's bad enough as it is.

As the world remains divided, this will likely exacerbate the issue for particular countries with lower birth rate. Immigration is one answer, but it doesn't always cover the population loss, and immigrants are likely to send a lot of their income back home anyway (again, this is absolutely not a case against immigrants, I for one welcome them).

Evening out population growth over time would go a long way to maintain a healthy future.