The USA has been able to get away with printing dollars because it sold things people wanted (an had to pay for in $) - the article alleges that this is no longer true.
There is nothing so significant the US exports which allows free reign printing of dollars. The US doesn't sell it buys - in fact it's the highest consuming country in the world. Even if there were exports the US could sell there is nobody which can afford to buy significantly. That's the economic drawback of having the near top currency.