Well his point was basically that nothing lasts forever, so he's right. But even so, the US has done a good job of playing the game post WW2. Testament to power in that the reaction to this will be mainly words from other nations.
Pretty much this, I wasn't talking about some "holy" crusade against the US or anything similar. My point was when the US system starts falling apart (by internal or external influences) it's going to end up bloody.
As for who is strong enough to take down the US, well China is a pretty good contender, Russia isn't that far fetched either (least we forget how history repeats it self(many times)). Agiel and some other forum goers have been drinking too much of the "US is unbeatable" propaganda coolaid that their country has been churning out.