There are some key differences between US and European economic systems:
More interesting part:
Read more here:
Robert Creamer: Why the United States Is Not Greece or Italy -- and Shouldn't Act Like It
You can never generalize on economic affairs. They are too complex. And people typically get fooled by the art of speculations.
Major question is that who is willing to fill the void that US may leave?
China is not willing to float its currency, as pointed out above.
In the world of economics, every action has a reaction. There are pros and cons of every major step.
If US goes down, the world will loose a major export market. The economy of every nation will take a hit according to its investment and economic ties with USA. The economies of the world are interlinked. If one big player goes down, the entire web will be badly effected.
This translates in to a BIG LOSS for China. Chinese members here shall not admit this. But they don't run Chinese economy either.
Today WESTERN economic bubble has blown up. Tomorrow, the case of China will be similar. And the story will continue. Just keep in mind that nothing is EVERLASTING in this 'materialistic' world.
Lesson is that don't put too much faith on any single side. Just play your cards as safe as possible.
Yes, this is a very dangerous possibility.
There was a big economic meltdown before WW-II.
Situation can change in the future. Americans know this.
US debt rose so high because of recession, Obama's policies, and WOT. These three will not remain forever.