The trouble with buying futures is the counterparty risk. If things are as bad as I think they might be by 2013, I'm not sure who'll be around to honour such a contract.

See my longer post below. If you are long and the price rises you can withdraw your profits. The market works this way precisely to reduce counter party risk. I agree that a contract requiring delivery of $140 oil in 2015 might not be honored if it is $500 then but if you are attentive you should have withdrawn most of the gain before the expiration date.