Congress already made a deal to raise the debt ceiling, so we should have nothing to worry about (for now). One way or another, the US will be unable to pay its obligations due to the ever-increasing national debt. I'm pretty sure the FED will print more money (inflation) to "magically" sustain the American economy. People are beginning to lose faith in the corrupt banking system, so it should only be a matter of time before Bitcoin and other cryptocurrencies rise all the way to Mars.
The United States is quite wise to print extra cash so that it has little effect on increasing the rate of inflation in their country. They exchange the printed money supply for necessary goods in other countries and make sure that in the future large consignments of cash do not return back to their country. As long as the dollar is the universally recognized reserve currency of the world, it will not be afraid of default.