QE led to unbridles credit creation which is one of the drivers for higher food prices. That futures is a zero-sum game doesn't matter. Prices could be $100 a barrel for oil or $200 a barrel, and zero sum, and both situations would be the same. But for the common man this is not very positive, so they should definetely enforce speculator limits. UNG and USo have devastating effects on their own investors because of rollover, and on the price of oil!
I think the argument is much easier from both a psychological/animal spirits p.o.v. (unfortunately Alan Greenspan agrees so that takes away some of the merit of the argument) and from a fiscal p.o.v. I'd be willing to bet that the USD will no longer be reserve currency by 2020 (most likely EUR or less likely GBP or entirely unlikely but still possible RMB).