| Fertility rates do indeed have that effect, but it's buffeted most places by immigration that will continue to soften the effect for decades to come, so I think it'll be hard to predict how that exactly will play out. We can already see some differences quite starkly. E.g. Italy's fertility rate hasn't been above replacement since ca. 1975, and started seeing population decline a few years ago and is already back at the population level it was at around 2007, because it struggles to attract (and want to attract) enough immigration. Meanwhile, the UK dropped below replacement in 1972, and yet UN projections suggest the population is unlikely to decline until the 2050's at the earliest, and isn't projected to drop down to present-day levels at any point this century, largely buffeted by a far more aggressive immigration policy (including by politicians claiming to want the opposite - neither of the major party in the UK believes in reducing immigration, but some of their voters do, and that is likely to become a rising conflict). So while I agree some nations probably will see rapid falls, it really comes down to in part to what extent they are able to open their doors and find means of becoming attractive to immigrants fast enough while finding ways of integrating them in a working way. And this will reshape the political and cultural landscapes both within countries, and international influence. (one minor example, since we've discussed the UK and Africa: The UK is likely to soon drop from the 2nd to 3rd largest native English-speaking population worldwide - both India and Nigeria already have far more people speaking English as their 2nd or 3rd language, but Nigeria seems to be more rapidly closing the gap to have more people who speak English as their 1st...) > And this is also likely a vicious cycle because as age ratios and demographics get all screwed up, economies will start to collapse, which will make it even more uncomfortable to have children. Well, we may unfortunately in that case get to test whether fertility is inexorably linked to poverty or whether once it's declined it won't rise again. The other option is that as fertility becomes even more of an issue, we'll see a significant escalation in measures like the Hungarian (ramping up grants and subsidised house loans for families that get more children), but of course we don't yet know whether - or at what level - that will work... But I suspect many desperate attempts. Also, expect reproductive rights to become an issue, with more countries seeming movements to push back on abortion rights etc. using fertility rates as a reason. |
But I'd say here that you're not carrying forward that same reasoned skepticism when offering immigration as a solution. Because the exact same holds true. There are countless examples of mass migration throughout history, and they generally don't come with a happy ending. Rome, over the centuries, became an empire of immigrants, in some ways akin to the United States. Yet it was also ultimately destroyed by immigration. The Goths, fleeing the Huns, were take in as refugees by the Roman Empire. Those same refugees would ultimately go on to destroy the Roman Empire.
In the present day, mass migration doesn't seem to be fairing much better. Prior to the migrant crisis throughout Europe, many expected that the migrants would integrate, become part of the normal mass of people, and it'd ultimately be a win-win situation for everybody. That belief was not well supported by history, and ultimately proved to be false. And in the US today, cities that express an extremely positive attitude towards immigration tend to rapidly express a different view once faced with large numbers of immigrants.
And immigration on the scale we're talking about would be absolutely massive, and never-ending. And I'm not even getting into the countless social/cultural/political problems this would all entail. I'm merely focusing on the most extreme - would this destroy the countries engaging in such? And it seems to me that the most probable answer is simply yes. Well actually in modern times I don't think it'd destroy them. The most likely outcome is what we're seeing happen in much of Europe - parties that oppose the immigration would rapidly come to power, and end up working to mitigate the damage, and end such a population strategy.