Ah, the fabulous downsides. The problem with the Euro vs Dollar balance shifting too far is that it start wreaking havoc on the European nations that have the same problems the US has. I heard an economist a few weeks back outlining how nations within the EU that have uncontrolled budget problems will become unstable within the EU. Which weakens the flow of goods and labor within the EU, which destabilizes the global currency markets further, which makes oil more expensive, which makes agricultural and lumber products more expensive, and so on...