That’s correct, it depends on change on the money supply of fiat, which mainly depends on what central banks & governments do. However, they are trapped in the debt spiral. QE infinity and ever increasing deficit spending is inevitable.
Remember, there are three ways the US can lower its debt:
Austerity (lower spending to create surpluses) → political suicide
Raise Taxes → Likely political suicide that eventually leading to lower productivity anyway
Allow for higher structural inflation → higher nominal GDP leads to higher taxes leads to lower deficits (easy peasy)
Which do you think they will do?