It will be a viable strategy for decades, you're right, in as much as UN population projections don't show an actual global population decline until around 2100 or so.
The challenges that will bring, though, is policy, and which countries are attractive enough to "sit back" vs. being forced to offer increasingly attractive incentives, and where it will cause substantial political complications.
E.g. China is notorious for it being near impossible to permanently settle as an immigrant. I expect that aside from increasingly drastic measures to try to bring the fertility rate back up you'll see their first attempts be to entice the diaspora back to China, secondly an increase in rhetoric about One China towards Taiwan, and only well after those attempts to loosen up visa requirements for foreigners with no ancestral ties to China.
We'll see the return of diasporas increasingly becoming a problem for countries that has come to rely on certain immigrant flows.
A lot of countries will find political tension between forces wanting to more actively court immigrants vs. anti-immigrant groups becoming increasingly challenging and a major economic issue.
The challenges that will bring, though, is policy, and which countries are attractive enough to "sit back" vs. being forced to offer increasingly attractive incentives, and where it will cause substantial political complications.
E.g. China is notorious for it being near impossible to permanently settle as an immigrant. I expect that aside from increasingly drastic measures to try to bring the fertility rate back up you'll see their first attempts be to entice the diaspora back to China, secondly an increase in rhetoric about One China towards Taiwan, and only well after those attempts to loosen up visa requirements for foreigners with no ancestral ties to China.
We'll see the return of diasporas increasingly becoming a problem for countries that has come to rely on certain immigrant flows.
A lot of countries will find political tension between forces wanting to more actively court immigrants vs. anti-immigrant groups becoming increasingly challenging and a major economic issue.