People, including my dad, have been calling the doomsday BS since before Y2K. In 2008 they were getting on the bandwagon when the USD was down to around .60 against the euro, and oil spiked. And look at us now.
I do agree that it does have a chance to happen, we are really in debt, and slowly widening the gap between rich and poor. But then when you actually think about it, nobody wants the US financial system to crash, there is too much at stake in the rest of the world right now to let the USD devalue too much. If the population has no money to consume all the "made in china" things, it's not good for them.