The problem isn't localized to first world countries anymore, the process in all countries has already begun and cannot be stopped. Almost every country on earth has a replacement level or below fertility rate and every single country has a fertility rate significantly lower than 30 years ago. A generation has already grown with the lower fertility rate, which means a generation is already locked in that will age out of the workforce with barely enough young people to replace their productivity. It's done.
There might not be a sustainable solution, besides a brave new world, but I personally would like to preserve human dignity. It appears that steady state population sizes are a rarity in the natural world and that almost all populations are chaotic and fluctuate. https://fractalfoundation.org/OFC/OFC-6-1.html
This. Main point here: "this is not at all the failure of the West/Libs/Rich people/democracy/Jews/whoever else you want to blame. it's everywhere. don't look for culprits: it's just the natural process of economic growth and productivity improvement".
Well, that and the hostile response by natives to large migration is rational, to be expected, is naturally occurring and cannot be stopped either, regardless of the fact that it is unavoidable.
There might not be a sustainable solution, besides a brave new world, but I personally would like to preserve human dignity. It appears that steady state population sizes are a rarity in the natural world and that almost all populations are chaotic and fluctuate. https://fractalfoundation.org/OFC/OFC-6-1.html