If it were worthless then a loaf of bread would cos 1,000,000,000. So clearly it is not worthless The national debt does not directly impact the value of the dollar until the country defaults on its debt
I just bought $50 worth of groceries and $40 of gas with American dollars, so it still seems to have some value. The Dollar has also traded well against the Euro, Yen and Yuan lately, so as long as we back our debts with the "full faith and confidence of the U.S.." the dollar will be ok.
It may not be worthless, but over time it seems
to be worth less every year.
We are in debt to ourselves. Not a huge crisis in my opinion.