Here's a hypothetical scenario which I doubt has any plausibility, but let us considerate.
What would happen if every country in the world made a gentleman's agreement to forget all the debt every country has? Start it over, hit the reset button, make a clean slate. All that money everyone owes everybody else now, you don't owe it anymore.
What impact would this have? How would the global economy respond? Who would be winners and who would be losers and just how big would those wins and losses be?