The good news is that Social Security and Medicare are not actually liabilities. Congress can refuse to make the payouts, or (more likely) modify them as Paul Ryan is proposing, and it will have no negative impact on the nation's credit. If anything, gradually reducing the payouts over time will improve our credit.
But that isn’t going to happen without blood in the streets. The only way for it to happen is for the older generation and the sick and weak to die out with a quickness.
SS and Medicare are unfunded liabilities. SS has already been borrowed against with only 2 paying in and 1 paying out. I think it is close to 1 to 1 now. Either way it now requires borrowing money from other countries to fund them. China isn’t buying our T-bills much anymore and the Fed has jumped in to pick up the slack. From what I have read the Fed is getting close to the point of not being able or willing to purchase anymore debt from us either.
We are now past the point of no return in paying off our debts even if we had double digit GDP growth. All anyone can do now is hope for the best and prepare for the worst. Make sure your tray is in the upright and locked position and you assume the position for impact.