Doesn't matter if you guys shun out the immigrant population and let ignoramuses multiply, while forcing American universities to toe the federal government's line for federal funding.
In China's case, the population decrease is actually a positive for them since they are primarily an exports-driven economy. A lower population means investing into automation at an extensive degree to retain the same production levels, without the need to feed that much of a population. And if China really needs an extra labour pool, they have no qualms doing the Middle Eastern playbook and bringing in tons of workers from low-wage countries to do the dirty jobs - in fact, they already do that with Africans.
Russia is in trouble though, but given that their industries are slowly being eaten by Chinese conglomerates, they are a has-been now.