So for example, during the late 90s, the CBO imagined ongoing surplus, and the eventual end of the national debt.

Now a phrase you hear a lot is "trillion dollar deficits as far as the eye can see."

But some of the best economists are predicting a rapid diminishing of the deficit.

In his 10 Questions For 2013 note, Goldman's Jan Hatzius wrote:

By 2015, we expect the federal deficit to be down to $500bn, or just under 3% of GDP. If this forecast is correct, concerns about the federal deficit are likely to diminish over the next few years.

Why will the deficit fall in half like this? Because of what we've been writing about a lot, lately: Deficits aren't about spending and taxes.