What if that isn't true though?
Fertility is universally falling in rich countries.
Could you give me a number of births-per-woman that would motivate your concern? I think 1 birth per woman is a reasonable number for national concern. South Korea is already at 1.0.
https://www.macrotrends.net/countries/KOR/south-korea/fertil...
Without a future generation long term concerns evaporate from concern. Maybe this has already happened in some peoples minds with regard to national debt, and the long-term sustainability of social security.