I am not an economist nor a politician. I do understand that a sovereign debt is as good as a country is still able to raise taxes to make ends meet. Greece does not have this luxury, because its citicen pride themselves of not paying taxes and brag about it, besides the normal corruption and political bribes. Italy is not far behind, a bit more " sophisticated going about it ".
The UK is almost in the same position, except nobody wants to talk about it.
The US of A is in a more precarious position, because the politicians, run by their ( few ) voters, can not and will not raise taxes. To create jobs ( workers paying taxes to the treasury ), will take a long time and patience and our friends south have little of this.
So why would I run to the mighty US $ ?? A safe haven ? No !
When the " fan " hits the " cow droppings ( where is Ganalane ), the freckles will show when they come down.