Iraq is not an island, but DC sure is. And here I'll inject my own pessimism: It would be political suicide for Obama to change his stance on Iraq--even though it is clearly the right thing to do. We've reached a point wherein hand-waving rigidity is lauded as righteousness (in both parties) and nuance is punished swiftly. Never mind that Obama drafted his plan for withdrawal a full 18 months ago, or that the drawdown from the surge is behind schedule, or that Maliki is emboldened by recent successes, that Bush is kicking the can down the road, or that General David Petraeus has declared that we won't know we've made progress "until we're six months past it." The pitchforked mob will have the flip-floppers, dead or alive.
But the Obama campaign, it seems to me, is fueled by the opposite conviction: that we can use reason in politics, not dumb-ass Morris-Rove tactical blather. On an issue as profound as this one, there is no need for a U-turn; the goal is still withdrawal of all troops as soon as is prudent. That's all Obama need say: that he wants us to leave entirely as soon as makes sense. He was against the war from the beginning, which makes him a far more credible advocate for withdrawal than McCain.
I guess I would never have supported Obama if I thought he were incapable of prudent, pragmatic adjustment in policies. We'll see.