Currently the debt per taxpayer is $187,000, about $9000 of which came just this year. Obviously this isn't ever going to be paid.
You can play with policies to reduce the debt in this little game. For most people, it's pretty difficult to do it while worrying just about your own ideals, but imagine that you were a politician who also had to satisfy your largely-clueless voters. It's not happening.
It won't necessarily be the next generation:
- By 2025, interest payments on the debt are projected to exceed the military budget.
- By 2026, the Medicare Trust Fund is projected to run out of money.
- The median baby boomer will retire in a couple of years.
- Some predict that we're in a bond bubble that's coming to an end, leading perhaps to much higher interest rates within a few years.
- China, Russia, Iran, etc. have a strong interest in challenging the USD's dominance, especially as the US becomes increasingly aggressive toward them.
I think that the only realistic end result is the collapse of the dollar through hyperinflation. If interest rates quickly rise or if deficits continue on their current trajectory for 5-20 years, the debt will start to truly go exponential. Once this happens, the Fed will try to rescue the situation by printing money, but this will cause hyperinflation, and the world will lose faith in the dollar. A worthless dollar "solves" the debt situation, but obviously it'd be a world-shaking event which would do enormous & widespread damage.
But because the dollar is currently the world reserve currency, this could take decades if nothing major happens to speed things up.