Thing is with pete if its outside of geo politics its outside his wheelhouse.
And when dealing with stuff outside his wheelhouse he goes with standard news which leads to a garbage in garbage out situation because the news organizations are well currently incompetent and compromised.
Everything listed above is geopolitics though? And it is ridiculous. Current population is 1.4 billion, deaths per year about 12 million. 2050 is 30 years from now, so your talking about 360 million dying over the next 30 years. So, taking that and zero births, children of men situation, the Chinese population only falls to 1 billion, not 750 million. And keep in mind China's population at this point is still growing: even if average births halve, that would still be 200 million births over the next 30 years.
If everyone over 50 was dead by 2050, that's only 331 million people. Compared to, as said a halving of births still is 200 million births, that's a net population change by 2050 of -130 million. Reducing Chinese population to "only" 1.27 billion, so a return to the disasterous population levels of . . . 2001.
His chinese demographic estimates generally seem to have little basis in fact, and require strange assumptions. A major famine reducing their population by 550 million more than expected, well, isn't particularly plausible. The great leap forward as a terrible famine killed 5-10% of china. That in the modern era is only about 130 million, and China is much richer and travel much easier today than back then.
If there is a famine that would kill 20% of chinamen, it makes more sense rather than let let 250 million starve, to export 250 million chinese to set up colonies and such.