I remember how under the Bush tax cuts and ensuing growing economy the budget deficit (although not debt) evaporated by the hundreds of billions rather quickly. I realize we're talking about a different set of economic circumstances and a drastically different degree of insolvency, but the model is there.
The limits are established by Hauser's Law - you can have 20% of GDP as tax receipts. That is it. Your ability to spend is limited primarily by GDP. 20% of 14 Triillion is 2.8 Trillion. CBO expects 4% GDP growth, but we all know that isn't going to happen, but if it did, we would have a 20 Trillion GDP in 10 years. You get 4 Trillion in revenue then - that won't even pay for Current spending. The unfunded liabilities will grow at a much higher rate - 6-10%, add in the interest on our debt, and this is over in less than 15 years- and that is the pie in the sky happy,happy joy, joy scenario. What we really have had is under 2% (because the inflation makes it look like it is growing). If the economy does pick up, the fed will be forced to raise interest rates - and hence what we pay on our debt. Even if it only rises to 3%, that is enough to run us over by just the extra we have to spend on entitlements.
When you need 10s of Trillions and you can cut by 100s of billions, and you need to do it over decades, the math simply does not work.
Believe me, I didn't cash out my 401K and spend my life savings on prepping for a "maybe"
There is no way the Math works without dramatic changes in entitlements. The Ryan plan is a good place to start, but it falls short because it is based on the CBOs rosy expectations of 4% growth. Less than that, and you get less time.