As of now, the largest holder of U.S. Government debt is the Federal Reserve System (something ignored by the mainstream media), and I would look for this situation to accelerate rapidly, as the government is going to claim it now can fund its expenditures with "free money." No doubt, Paul Krugman and the others will promote the fallacy of "we owe it to ourselves" and that there is no opportunity cost in the Fed directly monetizing government debt.