[Barrin92]

That last part is a little bit of an understatement. With South Korea's birth rate at 0.8(!) they're effectively extinct in five generations. Economic and technical success can come and go, eliminating your biological and material basis for existence is the only non-negotiable thing if survival is what you're interested in. And it's a cliff. You can dig yourself out of a recession in a decade or two, once you've cratered your demographics you're done for the foreseeable future, because even if you raise the birth rate back to replacement, your cohort of young people in absolute terms is now so small is doesn't even make much of a difference.