Nah, stop using the US$ for trade is as simply as just stop doing it. There's no lack of infrastructure, and plenty of commerce doesn't use it already.
What is hard is desinvesting from the US treasure. You have to sell those somewhere, and if everybody tries, their value will quickly go to 0. But if the US is successful in making their trade-balance positive, this will solve itself without a lot of hardship, it's just a matter of the rest of the world helping them here.
Macroeconomics is not what will show you problems here. The US is inserted itself into every supply chain on the world, but you will only notice this if you look at the details. Maybe we should start with an intellectual property reform...
Hum... What kind of tsunami do you expect to come from some thousands of people holding dollars for a few fewer milliseconds?
That would take a lot of legwork to confirm, but while the US$ is certainly the most used intermediate currency, it would surprise me if it was even used on the majority of the transactions.
