Rich countries will just keep importing labor. The large aged population will throw out any government that threatens their quality of life in retirement.
Middle income and poor countries with low birth rates may suffer greatly from having their working aged populations poached.
This only works so long.... We are running into the issue where almost no rich countries are producing excess population. Couple that with the countries we think of as excess population producers have massively reduced their own birth rates, then one day those rich countries will start having to pay very large amounts for imports, hence threatening the quality of life by increase costs.
This is an article about Korea, a country which is not doing so, and is quite likely incapable of doing so in the quantities needed to offset a 0.7 TFR.
Middle income and poor countries with low birth rates may suffer greatly from having their working aged populations poached.