Well, we see unintended consequences of their one child policy.
Not only do they have too few young people to support an aging population, but a shortage of girls, because so many people wanted their one child to be a boy.
I’ve decided the hectoring about demographics is BS
Its the justification that statists and social engineers in Europe and the USA now use to import millions of illiterate, un-assimilable, in-bred immigrants from the 3rd world into Europe and this country. I’m convinced its the scare-mongering of progressive-leftist and their evil twins in crony-capitalist finance who simply are facing a maximum debt armeggedon and need to find some way to keep the game going with more taxpayers and supposedly productive citizens to milk.
Populations rise and fall over the centuries due to health/disease, peace/war, economic stagnation or growth, etc... Japan and Korea are facing the same demographics as the West, but have chosen cultural survival over mass migration to support their economic edifice. They will figure out the problems for themselves. And I guarantee you - their societies will exist long after the Cultural Marxists in the West have destroyed ours.
Without a doubt, the Marxist social engineers in China have created a huge problem for themselves. The law of unintended consequences and blow-back are hard for tyrannical central planners - but using the failed Western Progressive outlook to judge the failed Eastern Marxist situation is just stupidity times two.
It could become worse than expected. When a country industrializes its productivity initially surges but then tapers off. And as a country becomes affluent its birthrate declines.
Should these generalities come into play for Red China, it will have significant challenges. When faced with significant challenges, count on political leaders to make a hash of it!