Obviously one can question their growth assumptions, and therefore tax revenue assumptions.
However bear in mind that this chart is for the expenditures as a percentage of GDP, and is therefore tied to the growth.
Personally I would think that they would lowball the interest payments, which are not so tied to the CPI as COLA increases in things like Social Security. Bondholders are not as captive an audience as your old people.
But as I always say, until the financial system is reformed and the economy is brought back into balance, nothing will 'work,' whatever combination of austerity, stimulation, growth, and tax changes it may include. This discussion is the misdirection and distraction, the financial magician's tools, from the actual transfers of wealth being conducted, those transfers being a nice way of saying 'looting.'
The US resembles post Soviet Russia just prior to its currency collapse and the rise of the oligarchs who sought to monopolize productive assets which they bought with paper and financial manipulation. Communism died, and it ended in oligarchy. Democracy is dying, and it too will end in oligarchy, unless something is done to change the outcome.
