I'm not an economist either, but there are a few things.
The US economy is in real trouble with debt. Those who deny that like to point to the 1980s, but in the 1980s the US was owed more by other nations than it owed. That is no long the case.
The falling US dollar could very well result in the Euro being the currency of choice around the world, including with the OPEC countries. The OPEC countries are looking at change not just because of the value of the dollar or because most of their customers are in Europe, but because US belligerence has angered them. If they can convince the Saudis, OPEC will go to the Euro. That would lead to more debt and a higher trade deficit in the US.
The US badly wants to invade Iran. That's been very clear from the rhetoric coming out of the Bush administration. Nobody will back them (Paul Martin and Stevie Harper might try, but the Canadian public will squish them if they do) so they'll be on their own. It seems likely that George Bush will push ahead with anyway though...he wants it bad. Wars are incredibly expensive so the debt will rise massively again.
He can run an expensive air war for about six months before he has to send in ground troops. That means a draft. Even if he doesn't invade Iran he likely needs a limited draft though...his military is not big enough to deal with its obligations. That means massive civil unrest at home...burning draft cards, riots. We've seen it all before. That's all expensive too, and bad for the economy.
While all or part of that is going on, Europe is going to expand trade with China, so neither will be as dependent on a shrinking US economy.
Then there's Korea and Taiwan. Bush has handled both badly and while China doesn't want nukes in North Korea either they aren't willing to let the US expand its power in the area. Taiwan could turn into a minor shooting match if that happens China could well decide that its time to destroy the US economy. They hold a massive amount of US debt and if they revalue their currency upwards, then sell off the debt they can break the US bank.
I think the world has had enough too. Everybody was hoping that Kerry would elected and the problems could be addressed. Instead not only did Bush win, but his first speech was belligerent and vindictive.
So far he has one major ally in Iraq, Great Britain. The war and Bush are both incredibly unpopular there though. Three British soldiers just got killed after moving to a more dangerous position against the will of the British people. That move was to facilitate an attack by US forces on Fallujah.
Kofi Annan just sent everybody involved a note saying that an attack on Fallujah would further destabilise things and make January elections in Iraq almost impossible to hold. No doubt that the timing of Annan's letter will undermine George Bush's standing in the world just a little more.
So that's how I see it. The US is still acting like it's an impervious super-power that nobody will dare to mess with. The fact is that they are incredibly vulnerable, both economically and, because of that militarily. They have no allies left, no friends, and have earned an incredible amount of animosity against them.
My biggest fear is that Martin is going to keep sucking up to them and we'll get dragged down with them.