Our total debt might pass the one quadrillion mark by the end of this decade - but if the interest payments have no direct impact on the lives of elites over the few months directly ahead, no one will care.
“As long as our dollar remains backed by the full faith and credit of the United States Marine Corps”
History suggests you have it backwards.
When the Empire can no longer pay the salaries of the Imperial Troops then the Empire falls.
That could happen with hyperinflation (so the salaries paid are in fact worthless) or it could happen with infrastructure collapse (where there is no practical way to get resources around the world). One other way it could happen is if the Empire splits by secession or other collapse so the currency has no value in international markets.
The key point is this—currencies don’t last very long in historical terms—a few hundred years is an above average run...