The only real concern at this point is Japan given how much they own. If the Bank of Japan must continue its aggressive yield curve control policy (BoJ buys their own credit/Japanese stocks), this would cause them to sell some Treasuries thereby putting some pressure on US credit markets.
But really not much, foreign demand for Treasuries is still quite strong.
@Mesooohahny sounds like they are talking about debt. The entity that determines when the debt will be paid is the issuer. They can send all the bonds back to the treasury that they like, but they are not getting paid until maturity. @NBS am I recalling this correctly?
More or less correct yeah, and I have no idea what Operation Sandman is. It sounds like bologna.
Foreign nations have zero incentive to dump Treasury holdings, particularly as most other sovereign credit looks like shit in comparison. Higher inflation elsewhere, more credit/default risk, etc.
Treasuries owned by anyone are sold in the open market, so natural buyers would also emerge. The likelihood they all dump? Zero. No evidence for it