The political and economic system of the United States is doomed. Elect whom you like in November, Clinton, Obama, McCain, the large-scale structural elements forcing a collapse will stay in place. A catastrophic collapse of our society seems inevitable.
The United States is no longer a democracy. I mean this not in the quibbling "It's a republic" sense; I mean that the government is no longer responsive to the will of the people. If the United States were a democracy we would not have invaded Iraq in the first place. Even if we'd invaded in a moment of temporary insanity, we would have been been out by 2006, if not sooner. If the United States were a democracy, George W. Bush — the worst and more importantly the most unpopular President in the history of the nation — would have at the very least been forced to resign (as was Nixon) and at best impeached or even prosecuted for crimes against humanity.
To be even more pessimistic, there's no possible way in an actual democracy Bush would be president in the first place, having actually lost two "elections" that would have shamed Ferdinand Marcos.
Even with the massive propaganda campaign, even with the so-called "liberal" New York Times leading the charge, even with Colin Powell lying his ass off to the United Nations, the invasion of Iraq was still so massively unpopular, and whatever support existed was so thin, that any sensible politician in an actual democracy would have realized that the war would be political suicide. That Blair supported the war, and is now reviled in the UK, just emphasizes my point.
The United States no longer has a free-market economy. While Capitalist economies have usually employed markets with more distributed economic decision-making than communist governments, there is nothing inherent in Capitalism that entails a free market. The definition of Capitalism is that the owners of capital are privileged to restrict the market as they see fit; a truly free market would not privilege anyone but the people as a whole to restrict the markets.
The United States is no longer a civil libertarian society. The Patriot Act, the Military Commissions Act, FICA, the War on (some) Drugs (used by some people), the ridiculous joke that's been made of the Fourth and Ninth Amendments, the astronomical rate of imprisonment. Need I say more?
The United States no longer employs the rule of law. Bush has explicitly and clearly declared himself and his minions above the law, and the Congress, the Supreme Court and the "opposition" political party have utterly failed to punish him.
The United States no longer has freedom of the press. The press, specifically the commercial media, has become completely dominated by a tiny elite of billionaires. It has become an organ of partisan Republican propaganda differentiable from Pravda only by its sophistication and professionalism (and sometimes not even that).
The above are not just bad in themselves, they are fundamental error-correcting mechanisms. When you lose error-correcting mechanisms, errors accumulate until the only ineluctable error-correcting mechanism — reality — causes a catastrophic failure of the system. Even if we were to elect Obama or Clinton, even if they were completely well-intentioned, even if they had the power to kill with their minds, they could not reverse our path to catastrophic failure. Things will have to get much worse before we can even think about any major structural changes.
Catastrophic failure is bad, but humanity will survive it. We've survived catastrophic failure time and again: World Wars I and II, the Great Depression, the Panic of 1873, etc. ad nauseam.
What's more worrisome than the collapse itself is the aftermath. There's only one group ideally positioned to take power after a collapse: Christianist extremists. They've openly infiltrated the US military. Their civilian militias are well-organized, well-disciplined and extremely well-armed, and they enjoy the active tolerance of the Justice Department. They have a definite, elaborate and fanatical political agenda. They have a good 20-30% of the population firmly on their side, which was enough for Hitler after the collapse of the Weimar Republic.
If we're lucky, very lucky, "find a winning lottery ticket in the trash" lucky, some rich bastard like FDR will pull our nuts out of the fire at the 11th hour out of desperate self-preservation. But if FDR had faced a Communist party with the organization and armament of today's Christianists, we might well have ended up with Joe Steele instead.
Perhaps there is, however, some reason for hope.
As well-armed and organized as are the Christianists, their ideology is extremely loopy and insane; by comparison Nazism and Stalinist Communism are models of rational clarity. They're already extremely sectarian; they'll spend as much time and energy fighting each other as they will the rest of us. I don't think there's any alternative but to fight them, but they can be beaten.
[Update: I'm with Tim Kreider: I plan to be drunk off my ass when the shit hits the fan.]