Ehh... we've been arrogant for the last 100 years, and if anything, it's a self-fufilling prophecy to a degree. What will be our undoing is material shortages, which puts the US in a timeline for trouble in the next 50-75 years. Our industries are still too disconnected, and we could maintain global economic superiority by interconnecting industrial processes more to reduce environmental impact while improving effeciency, and moving more completely to an information-based economy.

The US military is so powerful and organized so that it can exist with central disruption, and basically retaliate against any force in the world, devastating it completely... as long as it's another nation. We still do not know how to win a war against an ideology, which began with Vietnam, continued with our unsuccessful attempts against revolution in South America, our continued failure in the "War on Drugs", and now Iraq.

The only reason we came out of the Cold War in OK shape is that communism is a HORRIBLY ineffective way of managing a national economy and modern production.

(BTW, I'm highly against US meddling in the political affairs of foreign states... but I was using that as more of a point than a recommendation)