It appears as if the insurgants in Iraq are going to emulate Robert Mugabe and chase all the Christians out. If they succeed, they might also end up copying Mugabe in other ways, as their country loses a large part of its economy. Not that Iraq will turn into Zimbabwe--it takes a special kind of person to do that!--but it could well turn into, say, Nigeria or Venezuela or (ha ha) Russia.
This is a problem I didn't anticipate (I was, and remain, fixated on the Kurds as the source of long term instability and ungovernability). But I suppose this is another good one. An it shows up the fundamental point that one really can't predict what's going to happen when one creates a new nation. Which is why we should be really careful and hesitate long and hard before doing so. Because it ain't going well. And Dick Cheney aside, there weren't any weapons of mass destruction there, and there was no reason to invade.
And perhaps another thought. Maybe it'd be a good idea to NOT assume the best case scenario, but prepare for the worst.