David Frum argues that the U.S. must remain the world's top dog:
The prospect of the U.S. as number 2 is a threat and challenge. So long as China remains a repressive authoritarian oligarchy, the prospect of a world reordered to meet Chinese imperatives is an ugly one.
The U.S. has only been the undisputed leading global power for about 30 years, meaning that for most of American history we have had to contend with either equal or stronger global powers, some of whom did not share our values and had conflicting interests.
Additionally, China has not proven that it can reorder its own backyard (although it clearly wants to) and they have never evinced any sign of having the kind of global ambition that so regularly infects America's Wilsonians and neoconservatives. And even in the event China overtakes the United States and suddenly decides it wants to exert its benevolent hegemony over the world, it would be opposed by a coalition that would likely include - at a minimum - the EU, Japan, India, Australia, the UK and the United States. Almost every major power, that is, except Russia and Brazil. China might find it rather lonely at the top.
A world with a more powerful China will not pose any ideological threat to the United States or the idea that free-market capitalism is the best way to organize a society. The biggest threat to that idea are the free-market capitalist societies themselves, which are busy imploding or staggering along with sub-par growth. Righting that ship has very little to do with the relative position of China - and would be the right thing to do with or without the prospect of a rising China. And China has already embraced the market (albeit with a heavy dose of state interference). Moreover, the lack of freedom in China's one-party state is not something that they have expressed much interest in exporting to other countries.
By all means the U.S. should take China seriously - more seriously than it has to date. As far as potential challenges to global stability goes, the territorial disputes in Asia are arguably more dangerous than an Iranian nuclear weapon. But we're not facing a Cold War style contest for global supremacy. Acting otherwise is not conducive to clear-headed thinking about what the U.S. does next.