Let's see: Ignoring other obligations, the National Debt is about $19.1 trillion. The government took in $3.25 trillion last year and spent $3.69 trillion. If they raised taxes by 12% and dropped expenditures by 12%, we could pay off the debt in about 50 years.
You're right. that will never happen.
But if we raised taxes by 6% and dropped expenditures by 6%, we could eliminate the deficit, so that the debt would stop growing. Then if inflation in the next 50 years is the same as the last 50, the $19.1 trillion will turn into the current equivalent of $2.5 trillion: i.e. we will inflate away 87% of it.
And the unpaid pension obligations?