At the same time though, as long as western Europe continues to have its debt woes and fiscal austere measures, the US economy in terms of bonds and treasuries will still be a safe haven for global investors. First it was Greece, then Ireland, how's the saying go 'there's never just one cockroach'.... Portugal, Spain, Italy...
Also, this whole QE2 is meant to some degree create slight inflation (funny how we admonish China for tinkering with it's currency and do the same damn thing).
Here in this 21st century in the age of globalization, the economic super powers (i.e. G8) will continue to set policy in very close tandem (imo)