In his recent entry on Znet, Chomsky says:
"There are two ways for Washington to respond to the threats engendered by its actions and startling proclamations. One way is to try to alleviate the threats by paying some attention to legitimate grievances, and by agreeing to become a civilized member of a world community, with some respect for world order and its institutions. The other way is to construct even more awesome engines of destruction and domination, so that any perceived challenge, however remote, can be crushed – provoking new and greater challenges. That way poses serious dangers to the people of the US and the world, and may, very possibly, lead to extinction of the species – not an idle speculation."
I don't think it will come to nuclear war, unless the folks in DC try too hard to pry loose the regime in Beijing. Yet I don't really see any end to the arrogance of the Project for a New American Century crowd. So here's my nominee for a more likely future. The US invades Iraq and creates a major humanitarian disaster, unaccompanied by emergency funding, most of which was taken away from the AIDS disaster in Africa to deal with America's two Asian wars. The UN becomes a rubber-stamp for US militarism around the world. The ruling classes in France, Germany, and Russia cave, and attempt to re-establish normal relations with the regime in DC as if nothing had happened. They soon learn, however, that if they want their economy to run, they had better plan for a source of oil, and Iraq's oil will by then be firmly in the control of one Tommy Franks. Iran will not be an alternative, as the US will be invading it soon, as well, and Saudi Arabia will be holding on to every US batallion it can get in exchange for whatever is left of Prince Abdullah's power-base.
Then the Global Hubbert Peak hits, somewhere around 2010. All of a sudden it's time to convert to alternative energy sources. But the US, as well as the rest of the world, has been putting all its energies into coping with the Bush/Cheney Administration's foreign policy debacles. (Oh yeah, in 2008 Cheney is elected President, and the Democratic Party disappears as a viable alternative.) The popular opposition in the US, the "progressives," are preoccupied fighting the Bush/ Cheney Administration's re-establishment of the military draft, while the price of oil, having been so cheap in the US for so long (remember we've got that Iraqi supply!) skyrockets out of sight. The economy collapses. A "state of emergency" is instituted, the President is given dictatorial powers, and the Constitution falls into complete disuse as martial law is proclaimed (since the military is granted a monopoly on oil by its sponsor, Exxon/Mobil). Revolts within the military become widespread and are crushed brutally. The economy of the rest of the globe regresses to feudalism.
Now, remember, folks, that's the LIKELY future. It basically discounts the role of public opinion in shaping the future. Now, it's reasonable to expect no role for public opinion, as history is more likely to shape public opinion than public opinion is to shape history. But that could change.