Khruschev said 50 years that the USSR would "hang the USA, and we would sell him the rope to do it". That one didn't turn out either.
Honestly, I think that China, Russia and the EU will do most anything to prop up the USA. Because if the USA fell, the whole world would be sucked into a depression that might exceed the 1929 one. However, monetary instability may cause everyone to agree on one world currency. Evangelist will LOVE that one!
I've heard this crap before, I remember back in 1979, everyone talked in whispers about a US monetary collapse.....didn't happen.