In a way, the bond market tracks international central banks' confidence that this will continue to be true. If they lose some of that confidence, their stock of bonds moves from USD to RMB/EUR/JPY/AUD/CAD/SGD/etc.
RMB - maybe, but nobody sane trusts China to not immediately change priorities on a dime
EUR - imho (much) less chance than RMB, but they're using a hack: of EUR is a massive entity and internally there's no choice. Literally not allowed (due to tax reasons) (exceptions of course made for favored entities) (I feel that those favored entities exist, and how big they are, should be a huge red flag for anyone considering using EUR)
JPY - can't project force ... and doesn't even try
AUD - no
CAD - no
SGD - no
I don't understand why you're not listing GBP, as they have at least at some point done this. Of course they were a worse steward of international trade than the worst point of the US. Also, you consider AUD, but not CHF?
So what choice is there, really? This is really a way to try to push the US to do more, for less "exorbitant privilege" (especially EUR). Of course, a great many people are very interested in doing just that. It strikes me as an extremely dangerous game to play. Yes, the odds of winning are good, but if you lose, you lose everything.
Global reserves continue to hold USD in greater quantities than anything else. A movement away from the USD still means a relative loss of faith in the US. If there's nobody who can guarantee trade then you still need to hold reserves, right? You just have to hold a broad and shallow pool rather than going deep on one currency.
Given the history of economic sanctions (what the EU is doing) ... of course people don't know that history, but the TLDR is that nearly always economic sanctions are a prelude to war. They don't just not work. In many cases they cause wars. WW1 was caused by economic sanctions (and the scale of EU economic sanctions is 100x bigger than what caused WW1), and often the economic sanctions on Germany after WW1 are generally thought to be the big reason for WW2. It makes sense from a game theory perspective: if a government, whose power is fundamentally based on force, lets economic sanctions convince them, they will be attacked by their own people. So they simply cannot give in, and historically that's what you indeed mostly see: when a country is targeted by economic sanctions, it's government usually decides to attack.
The EUR is imposing very large scale sanctions on ... essentially everyone. Russia and China most obviously of course, but sanctions are so widely used by the EU you can literally say it's being used against everyone from Afghanistan to Zimbabwe, or geographically from Paraguay to North Korea. And why is the EU doing this? Exactly the reason Trump is doing it: sanctions are "power without needing parliament to approve the budget for anything".
The fear is: the historically most likely outcome of what the EU is doing, what EUR is being used for, is another very large scale war.