First: Great discussion! Sorry I've missed out on so much of this...
If we accept the number from Haganes of 90% of oil reserves owned by national oil companies as a given, I don't think this does much more than confirm that oil is likely to be a commodity market for the forseeable future.
Why? Simple: Oil is found in quantity in many different places in the world. While there are definite application preferences for different kinds of crude, you can pretty much make any petrochemical out of any crude oil.
If commercial entities owned all the oil, they'd probably consolidate into a few megacorps (which the oil companies pretty much already have) and would then oligarchically agree to set the price for oil at so much a barrel.
Nations, of course, are lousy team players (witness the entertaining internal politics of the EU as an example). Nationalism doesn't mix well with oligarchism. As long as Hugo Chavez, King Abdullah, Vladimir Putin, Fidel Castro, Olusegun Obasanjo, and Stephen Harper all have say about a certain large chunk of available crude oil, you can rest reasonably assured that they're not going to manage to agree to a price and stick to it. Somebody will get greedy, or grandstand for political purposes and undercut the others by a nickel or $5 and start a price war, as often happened in OPEC over the decades.
That said, it's an irrational commodity market. Prices are set more by buyer fear than by logic. A reliable way to get more money out of a barrel of oil is to keep the perceived reliability of major oil suppliers (like Nigeria and Venezuela) low. It could also be said that the current adventure in Iraq mostly has served the purpose of keeping Iraq's oil reserves off the world market for a number of years to come.
What does all this mean? Well, it means that it's smart to either a) take the Roman approach and set up actual commercial colonies (which is currently unfashionable), or b) find a way to reduce the consumption footprint of your nation and yourself. The less oil you need, the less you are likely to be bothered by the unpredictability of the market.
"The Stone Age did not end for lack of stone, and the Oil Age will end long before the world runs out of oil"
--Sheikh Zaki Yamani