James Kwak updates his projections in the article Updating October’s Long-Term Debt Projections. He concludes:

The most important point remains the same: If we let the Bush tax cuts expire, the national debt will be significant and rising in the long term, but will not be that much larger than today even in 2035. Which means that the national debt problem over the next twenty-five years is as much about tax cuts as about entitlement spending.

Ben Leet commented on that post as follows:

As Dean Baker and Jeff Madrick say repeatedly, the health care system is the driver for high federal deficits in the years to come.

They may both be right.  Note, that if we were to fix the cost problem for the government funded part of the health care system, but did not fix it for the privately funded part of the system, health care would still eventually take 100% of the GDP.  The issue of the rising costs  of health care progressing at the current rate is completely independent of whether it is paid for by  the government, direct payment by private citizens, or funded through employers.  The result on our economy will be devastating.