The US is not going to default. I doubt we will even miss a microscopic T-Bill payment. At negative nominal rates, does a "missed payment" mean the holders send more money to Treasury? Elvis has left the building.
The ECB feels it should raise the finance rate as the actual default of one of its members takes place. I studied at a different school. Derivative products designed to "hedge" such an event will, of course, not be enabled. The whole thing is just sad.
The debt market is going to embark on a discussion about price. Too long in the fantasy of QE, its time to see what Mr. Market thinks. As Martha Stewart says, "It's a good thing." Oh, its the title you are wondering about? One of my faves.