the other oil producing countries don't want an economic depression either - what are they going to do with their oil, drink it? an oil price rise to $80 a barrel won't last long - the economic slowdown will cut demand dramatically.
Okay, ~tinfoil hat starting to glow, propeller on top spinning madly~ the price spike need only last long enough or the switch in currency, long enough, until our economy is wrecked, our citizens standing in soup lines and begging for UN assistance. This would be more possible if there is further collusion (yup, I'm a conspiracy theorist especially concerning CFR and The Fed) with the Fed and other world banks and IMF.
Although, given current events and potential terror operations, it's possible that this scenario may be OBE (Overcome By Events) and that's even scarier.