China's working-age population will hold roughly steady until about 2030, after which it will go into a steep decline. This is already baked into the demographic cake.
If a rapidly shrinking working-age population weakens a country significantly, then China has about one decade left in which to increase its geopolitical power before demographic pressures start to bite.
Which is one reason I'm kind of worried about the 2020s.
In the runup to WW1, Wilhelmine Germany was afraid that every day, Russia's power grew relative to Germany's. It was one reason they wanted a war -- to beat Russia before it got too strong.
Countries that feel like they're on the clock can be very dangerous.
It's hard for some supporters of student loan forgiveness to understand the antipathy toward the idea. But I think a lot of it is this: America has developed into a class society divided between college-educated and non-college classes, and student loans felt like an equalizer.
In other words, I think many people look at the college-educated class, who earn more then them, get more respect, have nicer jobs, have more job security, suffer less employment in recessions, etc., and think "well at least I don't have to pay off a bunch of student loans."
That's not to say I agree with this attitude or that I feel this feeling myself. I don't. I'm just trying to explain it.
What we actually need to do is compress this class society back into a middle-class one, raise wages, improve job security, reduce unemployment, etc.
I'm in the razor-thin group of annoying people who want to keep the Senate but get rid of the Electoral College.
The Senate gives disproportionate representation to low-population regions. I think that's fine up to a point. But the Electoral College reduces faith in democracy every time it actually matters; it's only OK when you don't notice it. Thus it's a pure negative for our society.
While I don't have a position on @Peter_Turchin's theories overall, I do think that the idea of reducing immigration in order to raise wages makes no sense. Data shows immigration has little effect on wages, and skilled immigration actually raises wages.
If @Peter_Turchin wanted to make an anti-immigration argument, his "elite overproduction" thesis would be a more natural fit. He might argue that skilled immigration is displacing educated native-born Americans from the elite positions they had expected to inherit...
In fact, I think there is something to that argument. And I think it's a low-key, little-discussed reason why Dems will probably allow Trump's cuts in legal skilled immigration to stand...