One thing that I always remember from my political science classes is the idea of balance and rationality. To understand it, you must treat nations as individuals always (rationally) looking out for their self interest. It also serves that when one nation becomes very powerful, the next two less powerful nations will form an alliance of sorts to balance out the power of the first.
Right now, America is the hegemon. We are the hyperpower. But that could quickly erode, and then one day we will wake up - and look across the sea at a competing power that, through alliances of sorts, can challenge our hegemony. Then we will have gone from Hyperpower to Superpower. If we are truly unlucky, we will wake up one day, and we will be back to the instability of the Great Powers. We would undoubtedly be the Greatest among them, but that world is far more dangerous.
Here is how it happens:
The Russian Federation becomes alienated from the world.
"Russia has a choice to make," [American Vice President] Cheney said..."None of us believes that Russia is fated to become an enemy"..."[Russia has] nothing to fear and everything to gain from strong stable democracies on its borders."You're with us or against us, the wrong choice makes you our enemy, and we have you surrounded. Real public diplomacy.
China begins to exert its power. Their new energy partners? Nigeria, Sudan, Iran. Those nations would sell their grandmothers (and may already have, in some instances) to China for protection from us. Saudi Arabia's listening, too, Lebanon. (Lebanon?)
Do you think China cares about human rights in those countries? Do you think China is really worried about an Iranian nuclear bomb? Nope. And they don't have to be. Not as long as we're in the picture as the big bad wolf.
The real question is how far China is willing to go to protect their new sphere of influence. That question can be answered in Russia's willingness to thow in with China as a 'junior partner.' I guess we'll see just how well these bedfellows are in the sack when the West decides what to do with Iran. Despite our resolutions, Russia and China have already said they oppose sanctions on Iran's nuclear program, despite Iran's continued saber rattling. If we push the issue, we may get more than we bargained for.