then OBL/al-qaeda can declare victory.
Yeah, just like all the times they declared victory in Afghanistan.
If we did leave the Kingdom, one of two things would happen.
1. Iraq would move into the vaccuum.
2. Al-Qaeda would move into the vaccuum.
Both are good things. (1) would give us an excuse to move into Iraq and clean up Hussain. If we are smart (and Bush is), we start from the north and move south. Save the liberation of Saudi Arabia for last, so that the princes get a chance to really appreciate the magnitude of their decision to kick us out. (2) would give us an opportunity for "Afghanistan II -- The Kingdom." The House of Saud is not the only faction in Saudi Arabia. For that matter, we could maneuver things so the Hashimites rule again, as they did through most of the 19th century.
What everyone is hinky about is Saudi oil. Guess what? This ain't the '70s. The world economy is slack. Demand for oil is low. Further, Russia, Mexico, and Indonesia have slack production, and need money. Oil might bounce to $20/bbl, but no higher. Russia would win. Mexico would win (and it would ease calls for open borders). Indonesia would win. So would the North Sea producers. All of those folks are on our side -- much more so than the Saudis.
Let our friends win. Let the Saudis learn a lesson. Every other nation would draw their own conclusions, and be less willing to mess with us afterwards.