Earlier quoted context omitted.
Maybe people in the 90s assumed "prosperity" in general would be a panacea; but the hypothesis here isn't really to do with GDP more generally (because that can all be generated and captured by the state, as in middle-eastern oil-producing countries) but rather to do with a certain inevitable demographic shift. China has already started on a shift called industrialization : a massive demographic shift from poverty-cl…
You need to think of China like North Korea. There is very little chance they are going to democratize in the near future.
But China are still making construction workers into nuveau-riche at a prodigious rate. They're creating the proto-Rockefellers and proto-Carnegies of China, right now. Those people, and especially their children (who would become the actual Rockefellers and Carnegies of China), are going to have some impact. China might "manage" (i.e. suppress) that impact, but a large bourgeoisie class is uniquely powerful in terms of its ability to throw money around to influence foreign politics as a knife against the throat of the local state.
Consider: the Napoleonic Wars weren't a consequence of the French Revolution; they were the second phase of the French Revolution. Sometimes the best thing to do to get your government in better shape, is to convince every other major power that your state is the bad guy and needs its ass kicked.
Right now, China is (barely) keeping a lid on global unrest against them—but a big part of that is that right now, Chinese citizens are still mostly positive and patriotic about their homeland, as you'd expect of people who just went through an industrialization boom. Take that coefficient and flip the sign the other way, though...