It’s difficult to say what “cold comfort” means. It’s just shifted from one USD asset to another.
The exact economic effect is: “just depends.”
There is a ton of foreign owned equities for example.
USD could go into corporate bonds.
If China holds a lot of US Treasuries, I’m not sure it’s to their benefit for Treasury prices to decline rapidly as this would reduce the value of their remaining Treasury holdings. I could see them going for a gradual unwind, in the same way they gradually tightened their grip over Hong Kong governance.