Inflation, national and individual debt, the deficit, and the growing burden of SS and welfare programs on less people earning less dollars with a lessened purchasing power is gonna put the US in a pretty bad position. Few countries are outside of the sphere of influence though so they will be coming down with the ship to a certain degree. I don't think the US will outright fail, and there are still opportunities to succeed if you are savvy enough and make the right moves at the right time, plus safety and minimum living standards will always be very strong comparatively speaking, but there are some better options out there.
A quick way out is teaching English overseas, as some have mentioned. They have a very good program in the Czech Republic and also in Korea, amongst other places. Other than that, or securing some other work visa, it isn't easy. Some people think they can just up and leave indefinitely, and in some cases they can sneak by, but it isn't that easy really. Especially without substantial shoe-box money.