One Man's Trash
Unlikely. Hat Tip to Rich Lowry on The Corner for pointing out this article by Nawaf Obain:
To be sure, Saudi engagement in Iraq carries great risks -- it could spark a regional war. So be it: The consequences of inaction are far worse.
If we bug out of Iraq and Saudi moves in (as is supposed by the article above to be likely) then there will be yet another war between the Sunni & the Shia. However, Mr. Obaid points out the following possible weapon: OIL. However, it would be used in a different manner. Saudi would flood the world markets with oil driving the per barrel priced down. This would be very difficult for Iran to deal with whereas Saudi is better able to deal with the situation, or so Mr. Obaid states (I would guess it true, while Saudi Arabia doesn't produce much other than oil the Arabian Sheiks do invest their wealth).
However, it could come down to a shooting war larger than Saudi Supported Sunni death squads attacking Iran backed Shia death squads. If it does, look for new maps to come out. Iraq will be torn asunder and the situation would probably drive the Gulf nations to unite (with the possible exception of Oman which has a historical identity of its own) and grab a chunk of Iraq. Iran, of course, would help itself and then there is the problem of Kurdistan. Turkey would probably move against Kurdistan and this would really set something off as there is no way the Kurds of Northern Iraq would sit for being absorbed into Turkey.