That is cool and all; but if the US is going to seize assets after building a watertight legal case then countries can't just by default leave their sovereign assets in places where the US can seize them. A country's bankers are not interested in taking that sort of risk needlessly, there needs to be something in it for them.

Of course the international finance system is complicated so maybe there still is enough of a payoff to holding US dollars, we're seeing something of an exploratory process here as China, Russia and probably India start testing the system. It might hold.