So long as enough oil is denominated in dollars to satisfy US demand for imports, it doesn't really matter what currency other countries pay. A eurodollar crunch doesn't have any appreciable effect on US domestic prices and neither will a eurodollar glut. Petrodollars are eurodollars. [1]
To cut right into the meat of the issue, US issued currency will remain valuable until economic and political collapse destroy US consumer markets and productivity. Foreign asset holders cannot cause that by refusing to show up at treasury auctions. It would take a serious civil war, a world war where the mainland USA wasn't left untouched, or a similar multi-megadeath level catastrophe. And even then it wouldn't be impossible for the US to pull through as a going concern, as it were.
[1]https://ftalphaville.ft.com/2016/01/25/2151037/petrodollars-...