> their demographics are shaky AF

Every major country's demographics are shaky. Japan and S.Korea are already shrinking. The US is propped up by, uh, low-quality immigration, and fertility has nevertheless dropped to record lows. The large countries of Europe are either basket-cases, tinderboxes, or both. Germany and Italy haven't had above-replacement TFR since 1970!

China's not doing great, but having a population reservoir of 1.4B can make up for a lot of deficiencies. If everybody shrinks or becomes utterly dysfunctional, I'd bet that a vast, productive, essentially monoethnic nation weathers the storm better than the rest.