[dejb]

I agree that it is like a prisoner's dilemma. Perhaps more like the iterated version which does actually allow for cooperation to be the optimal solution.

I think countries holding large amounts of US dollars have a large incentive to talk up its value while quietly selling it off.

However those countries can probably use their influence over the US dollar to influence US policy and perhaps that is a benefit they have factored into to their currency holdings.

I'd say the chances of a collapse are unlikely unless the US decides to play 'chicken' with its creditors and is unwilling to align its spending and earnings.