America's not going to collapse. It's still a very rich nation. America has problems yes, sure, but ALL nations have problems. India and China, despite doing quite well, have problems too (namely, India has DIRE water shortages and religious problems, and China's One-Child Policy, which is going to be reversed soon, has created a shortage of young people).
Make no mistake, India and China are rising. Will they eclipse the USA? Who knows! No one can tell the future. But the US will still continue on, at least for the conceivable future.
The Americans always go through with this angst. First it was fear of the Russians, then fear of the West Germans, then fear of the Japanese, now it's fear of China and India. This is what happens when you become a super-power - you're consumed with fear over losing your position in the world.
The US is a strong country with some of the best technology in the world. Will the US have to, one day, live in a world where it ISN'T the only powerful nation? Yes. But does that spell doom and gloom for the US? No!
If the US survived the Great Depression, it can survive this. Yes, in the future, the US might become one powerful nation amongst many, but it will still have clout. It will just have to learn to live alongside others and realize that it might not always get its way. But that's nothing to fear.
As for gas prices - they've been higher. Plus, there is more than one way of generating energy. If Gas/Oil prices climb too high, you're going to have to build Nuclear Power Plants. Or Solar Power Plants. Or more hydroelectric dams.
The US deficit IS very large - but it can be overcome. Tough times are going to come about in the US, but again, that doesn't spell destruction.
If the US invests in Technology and Science, they will survive. And the US does invest in tech and science, quite heavily as well.
The real big problem with the US, one that is manageable, is your horrendously bad public education system. Make no mistake - US Universities are, for the most part, pretty damn awesome. You guys have Harvard, John Hopkins, Yale and a whole bunch of others, and they are all excellent universities. The problem is that your public education sector, your high schools and primary schools and elementary schools..... suck. They're awful. And your kids don't have any appreciation for knowledge, science or mathematics. Now, there are enough naturally talented kids in your nation to counter this - you've got kids so bright that they'll succeed no matter HOW screwed up your education system is. But the awful education system you guys have is creating a generation of ignorant adults, and those ignorant adults VOTE. Which can cause a hell of a lot of problems.
Take for instance - the Nuclear Power Issue. Current generation Nuclear Power plants are safe. Very safe. Japan and France have been using them for decades, and no accidents have occurred. Current nuclear power plants can reuse spent-fuel rods, over and over again, generating virtually NO waste at all. Compared to the environmental/human cost of Coal and Oil and Gas burning power plants, Nuclear Power Plants have killed less and created less of an environmental impact. If you truly wanted to lower the cost of living, improve the environment, and reduce the threat of Climate Change, then the US should be building Nuclear Power Plants like CRAZY. But you don't - because your population knows nothing of physics, and they all think that Nuclear Power involves Toxic Green Goo (thanks, Simpsons). Or what about Stem cell Technology? You lost years of research because ignorant Americans assumed that Embryo = Baby, despite the fact that an Embryo is microscopically small and HAS NO BRAIN. They didn't care to educate themselves on the science.
If anything brings down the US, it won't be gas prices or the economy, both of which are fixable. It will be the complete and utter disdain most Americans have for science and mathematics - the idea that "we done haf to listin' to them Ee-LEETs in their Iv-o-rey Towers! What, theys thinks theys better thans me just cause theys git themselves an Ed-u-ca-shun? Ta hell wit them! I learned everything ah done need to know on mah papa's knee! What do them scientists know? Nuthin!"