If the economy got sufficiently bad, in your opinion would the government cave in to calls for reforms? And if there's sufficient change in the west, how do you think that will impact it? Say people get a taste for it and America becomes predominantly liberal.
America in the 1920s is a decent example of China as it stands now, but I'd say Germany in the 1840s-1880s is a bit closer.
Germany at the time was growing very quickly from industrialization, but the reactionaries and conservatives were facing problems from rising bourgeois middle class, which advocated liberalism (in the European sense, though in the 1800s that was leaning towards libertarianism). The upper classes, which controlled the factories and provided the officers for the Prussian army, were largely content and supportive of the monarchists. The lower classes were poorly educated, and politically apathetic in central and western Germany (though the more bourgeois in a given area, the more likely the lower classes were to be liberals as well). In Prussia, eastern Germany and Poland the lower classes were largely illiterate and basically serfs, and served as the backbone of the Prussian military. It was only the rising middle class that posed a problem to the Junkers, and they rose up on separate occasions throughout the 1800s. On one occasion, they very nearly overthrew the Kaiser and instituted a republic.
But the monarchists were quite good at making the best of a bad situation. First, when the liberals were at their strongest (the 1840s-1850s), they instituted reforms that created a limited republic and parliament. Then they consolidated their industry in a fairly heavily State influenced direction, with the government being backed heavily by the industrial interests and vice versa. Once Communism began to spread, they indirectly supported the socialists at the expense of the liberals, and began aggressive imperialist wars to direct national attentions abroad so as to create a nationalistic pro-Kaiser fervor. By the 1890s, the liberals were basically powerless, and were completely overridden in 1914, the result of which I think we all know. By 1932, the liberals had effectively ceased to exist as a political force, and the last three or so liberal MPs voted alongside Hitler in giving him complete power.
Similarly, the pro-democracy types in China are relatively few and limited to educated people from the coastal areas. The people in the inland, who compose a large portion (if not a majority) of the army aren't sufficiently educated to consider democracy as an option and the present upper class is doing exceptionally well and doesn't want to rock the boat. There are only two ways I see China moving in the direction of democracy; the first is that the economy keeps going for long enough to create a substantial middle class, which would then support reforms which the ideal CCP of the future folds in on and accepts. This is unlikely (as a large portion of China's growth comes from nonsensical and unsustainable projects like empty cities in Inner Mongolia or from the rest of the world being in happy economic straits buying Chinese goods), and would only occur after a very long period of time. The other possibility would be that China falls apart and some of the SEZ's become vaguely Western influenced like Hong Kong. Neither is especially likely.
But also that massive debt thing is mostly a bunch of crap. Yeah there is debt but it's in very low interest bonds (actually negative interest inflation adjusted). Paying them off isn't that hard, our situation is only a little bit more adverse then it was in 1993 and a lot less adverse then it was in 1946. All we need is for democrats to control the government like they did in 1993 and for the country to not be in the middle of the worst financial crises in 70 years.
The deficit is quite a bit worse than in '93, actually. Not only that, the tried and true Clinton deficit reduction plan, specifically, looting the SS fund to make the balance sheets look good, won't work because the SS fund doesn't have much left to loot. Even the greatest of tax increases, assuming no economic problems resulting thereof, wouldn't come close to balancing the budget alone. Since the Republicans won't touch the military and Democrats won't touch entitlement programs, the chance of necessary spending cuts allowing for a balanced budget are basically nil, too (though just cutting the military or just the entitlement programs wouldn't be quite enough, even if one of the two sides did buckle).