> (Edit: granted, if all USD were owned by a single entity, the likelihood that such a policy would be revoked is much, much higher.)

If all of USD were owned by a single entity, the US Government just prints more. They will always have that power. That may cause inflation effects that they would be concerned about in the long term, but they have an immediate reaction lever to increase the monetary supply in such a (weird) hypothetical. (Though the correspondence between monetary supply and long-term inflation has always been much more theoretical "cause-and-effect" rather than showing practical, real world correlation much less "cause-and-effect". Especially this side of the Gold Standard the practical relationship between monetary supply and inflation is incredibly complex, and while you will find many people still presume an inflationary relationship the practical effects have been much weirder. [There are times in recent US history where USD monetary supply was at all time highs and inflation at all time lows.])

(Unless you hypothesizing an even weirder hypothetical where the monetary supply is increased by the US Government just handing the dollars to the single USD dollar holder and hoping that provides incentive to "trickle down" dollars back to everyone, but there's very little anyone can do with the onion of dumb in that weird hypothetical.)