Agree: in China's context (about which I know little, let's be honest), I would certainly not see the threat of the middle-class in its mass, as it would work in our countries where, right or wrong, at least 60 or 70% of the population considers itself as middle-class.

IMHO, its threat would rather be as a structuring element, a vanguard to use Marxist-Leninist jargon. When I parse through news articles on social unrest in China, I'm always shocked by how pragmatic, down to earth the claims are. The protesters want specific things: rescinding an abusive tax , the shutdown of a polluter, the money they were promised, etc. There is no overall conceptual demand, no political conscience, to go back to good old Marxism. They remain the lumpen-proletariat of Marxism lore, incapable of a revolution. If you throw educated members of the middle-class, that could change towards building actual political movements.

Again, not really knowing what I'm talking about, but I would hypothesize that something important happened to the power structure in China in the past 20 years. The Maoists were afraid of the intellectual class and made sure to bypass it and maintain their powerbase on army and skilled workers while keeping the peasantry at least moderately happy. Now, it looks like they have reverted willy-nilly to a more traditional authoritarian structure - high bourgeoisie -> middle-class -> working class/lumpen - the type most susceptible to revolutions because of the uncertain loyalty of the middle class to the high bourgeoisie.

PS: Same goes for India Except India is a real democracy and has democratic means to resolve conflicts that China doesn't have. For an anecdotal evidence, you should have a look at this NY Times article on highway building in India. It's slow, it's clunky but it works and people buy into it at every level. Why? Because of democracy, they can't bulldoze their way through. They have to negotiate. At a 30 years horizon, I'm betting on India rather than China.