Government debt is different from your personal debt, The US government could spend over $500 billion dollars per year in debt and not grow the debt as a percentage of the GDP, Government income to relative to the taxable money, as the economy grows, the population grows, and inflation goes, the government revenue also grows. Basically, the current GDP is 17.7 trillion dollars, so inflation(1.5-2%) with growth (3%) is $885 dollar increase for the following year, as long as the government deficit spending is that or less, the debt is as a percent of the gdp staying the same or shrinking.
So long as the US governments debt is denominated in US dollars, and the US government still controls the US dollar, then their is nothing to worry about, as debt is simply something governments have, and it is always measured in values comparable to the national GDP($17.7 trillion for 2014).
Only the most foolish of idiot governments would want their debt denominated in a foreign currency, or a currency in which the government does not control the central bank(see: Greece).
We in the US have neither problem, our problem is within our slash and burn politics of the right wing, that thinks massive cuts to the highest economic multiplier things in our budget(health care, social security, food stamps), will somehow not shrink growth to the point that it is negative, and reduce tax collections to the extent that the cuts have been canceled out(again see: Greece).