China, the most-populous nation on Earth, is now an economic force to be reckoned with. It is undoubtedly the most exciting business story of the decade, if not the most important geopolitical story, and it is the territory Ted C. Fishman examines in ''China, Inc.: How the Rise of the Next Superpower Challenges America and the World.'' By one estimate, China's economy — which today ranks as about the seventh-largest — could be 75 percent bigger than America's by the year 2050. China's future is not yet secure. For the moment, with China's economy charging ahead at 10 percent annual growth, more people probably are happy — or at least patient — than are unhappy, but any unforeseen calamity that derails progress — whether a banking meltdown or regional currency crisis — could lead to chaos. ''While all eyes turn to the so-called clash of civilizations between Islam and the West,'' Fishman warns, ''in the long run China will have the most profound impact on the world.''