When the legendary investor Julian Robertson speaks, you should sit up and listen. Read and Watch here.
Here is the 64 billion dollar question. If interest rates were to go sky high --if and when Japan and China were to stop buying US debt or start selling them, would US dollar also collapse in the face of high interest rates?
Answer, it depends on a number of other factors. Is inflation in the US or in the US dollar block also going sky high? if so, what is happening to the real rate of interest? The real rate is nominal rate minus inflation rate.
Another factor to watch: would domestic savings rate in the US remain low or high? If latter, that means US balance of payments could be improving, and then the pressure to sell dollar may not be a disaster. if fact, there might even be a dollar 'shortage' if US reduces drastically its imports especially from China.
However, if Julian Robertson is correct, and he usually is, US debt is not where you want to be. You can make a fortune short selling it. Which was what Robertson has been doing for sometime, according to his own public revelations.