This is why we have to separate money and state. No country should have the power and the monetary privilige to bully other countries into using their currency for trade. 
Discussion
Disclaimer:
"Any Country that tries should wave goodbye to America."
No country is being bullied and has every opportunity not to participate. He's simply stating that the United States is completely capable of being independent but are the other countries?
Remember when Europe wanted to buy oil from Russia but Russia only accepted Gold, Bitcoin, or Ruble as payment? Trump is doing the same thing.