In terms of efficacy I do not see how we exit Iraq, and leave it with a substantial chance for representative government (I hate the notion of democracy). However, from a political imperative, we will exit. There is bound to be a huge political vacuum and civil war with the Shiite dominating in league with the Shiite domination of Iran. At that point Iran will control territory on both sides of the Gulf and control 50% of the worlds oil. That is why Bush has said getting troups out of Iraq will have to be left to a future president. If a democrat is elected he, or she, will not even try to holdl the line. They will probably bring in Madeline Albright to manage the situation. At that point, which is only a little over 2 years away, look for Oil to spike towards 150 to 200 dollars per barrel or more. Then ruin comes with pain or an escallation in fighting into a massive world war.
Hey, but that is just me talking.