While discussions of Chinese power focus on statistics of their economy, few focus on the statistics of distance from China to areas of vital interest to us. South Korea, Japan, Indonesia, Australia, Thailand, Russia, and India are all close to China and Chinese power does not need to match ours to threaten us in real ways.
This article nicely summarizes a lot of the issues surrounding China's rise in light of recent revisions to China's GDP numbers. Basically, China's economy is less than half of ours rather than being over 80% of our economy.
The result? One, they can't afford to challenge us as once thought; two, they have powerful neighbors to pen them in; and three, they have lots of dirt poor or aging citizens that are a potential source of financial and political instability. Overall, China is far from overtaking America as the global power.
I've raised these issues time and again. Yet while I am not an alarmist over China's potential to match us as a global power (and even accept that China could evolve into a friend, as remote a possibility as that seems right now), I've also emphasized that China does not need to be a global peer competitor to harm our interests. Remember, neither Germany nor Japan were global powers when they threatened our interests in World War II.
This is the Pacific Century, and the Middle Kingdom is for once an apt description of China after centuries of Chinese pretensions to that title. If China can dominate east Asia and the western Pacific, they may cow Japan, South Korea, and Australia along with the rest of the region by using that power to smash and occupy Taiwan despite our greater power and alliances.
China could perhaps decisively harm our interests just by being a bad neighbor.