To make things worse for the Chinese, they burned through the economic benefit of industrialization in only a little over one generation.
By comparison the British, who industrialized first, took seven generations to do it. The US and western Europe took five generations. Japan did it in three generations. The faster a nation industrializes, the faster they see the demographic collapse.
Demographically, the United States is in the best shape of any industrialized country followed by France and Turkey. Mexico is tops among the developing countries.
Japan has already seen the worst of its population collapse and is the model for how to deal with it. Their economy has been stagnant for 30+ years but it is still functioning very well. They have the world's second most powerful Navy and have allied themselves as tightly as possible to the US.
The absolute worst places to be for the upcoming demographic/ economic collapse are, rough order, Germany, Russia, Italy, China, South Korea, and the United Kingdom. The rest of Europe, minus France, Sweden, and Norway aren't looking so good either.
Economically, the best places to be are the United States and Mexico.
WWG1WGA
Garde la Foi, mes amis! Nous nous sommes les sauveurs de la République! Maintenant et Toujours!
(Keep the Faith, my friends! We are the saviors of the Republic! Now and Forever!)
LonePalm, le Républicain du verre cassé (The Broken Glass Republican)