Jim Hamilton used the Federal Reserve Flow of Funds data to present a question: who will buy “the additional $8 trillion in net new debt that would be issued over the next decade under the CBO's alternative fiscal scenario.”
I thought that the analysis was curious and too "partial". If one believes the deleveraging story, then domestic private saving is going to rise. The answer to his question seems pretty obvious…
Let’s say that consumption goes back back to the 1960’s-style 62% of GDP, then get ready for household Treasury accumulation. Spanning the decade of 1960, households held on average 30% of the Treasury's liabilities.
A simple example illustrates my point. If the Treasury’s book doubles to $16.5 trillion, and the household share of Treasury holdings rises to 30% – as of Q1 2010 the stock of Treasuries outstanding was just about $8.3 trillion (see L.209 here) – then households will accumulate over $4 trillion of those new Treasuries. That's just households, and holding all else equal (like financial funds and businesses).
So the answer is: the domestic private sector.