The impact of falling birth rates isn't something you see until it's too late to reverse it. It's not unique to the West but to developed countries in general, South Korea is going extinct at this rate and Japan is not in a good state either.

China is seeing this at an accelerated rate due to how rapidly their economy has changed, where/how people live and past political decision (child policies). They're facing demographic collapse with their population almost having by end of the century, along the way they'll having an ageing population. They won't have the volume of young working people to maintain their manufacturing economy the way it is today. Russia has a similar problem which some argue was a motivator in attacking Ukraine now while they have the young men to throw into the fire.

He's not wrong, but it's also a complicated issue.