The errors of definitions multiply themselves according as the reckoning proceeds; and lead men into absurdities, which at last they see but cannot avoid, without reckoning anew from the beginning.

Personally, I don't see what the problem would be with a democratic, representative government that was of a more federal structure. Shias, Sunnis, and Kurds would all be guaranteed representation. Heck, I want that here in the USA (fat chance).

The problem might be religion, right? That's what I keep hearing (Huffingtonpost, L.A. Times, look up more yourself, it's easy!)

But according to the Economist,

These two groups—the Shias generally more pious, the Kurds more secular—seemed to reach a fair compromise on one major point, the role of religion in the state. Islam is declared to be the “official religion” and a “fundamental source of legislation”; no law should contradict “the tenets of Islam's jurisprudence”, and the constitutional court will contain experts on sharia law. However, the draft gives roughly equal weight to the “principles of democracy” and to human rights, and contains a broad list of political freedoms.

I have to be honest, I don't think the United States could do any better if we had to start from scratch today. Hell we already have our own controversies about courts full of experts on religious law.

The reason the Sunnis are against federalism is because they fear losing the southern part of Iraq to the Iranians. In all honesty, that's a legitimate concern, since the world is so keen to drop and run. Whether you think we should have invaded Iraq or not, we did, and we are responsibile for the outcome. A strong centralized government will pit one ethnic group against two others. A federation-style government could literally put Iraq's fractions on the map, making the post-Euro-colonialism artificial nation a part of history. Either way, the more quickly we leave them to fight each other, the bloodier it will be.

From the Economist:

The Iraq Security Force (ISF) has fewer than five battalions able to operate without heavy American support. Several dozen more are expected to become ready over the next year. Currently, every operational ISF battalion is mentored by a team of ten Americans and backed up by an American unit to keep it out of trouble. Formation of support elements—medics, engineers, and so on—is still rudimentary. And the police, numbering 65,000, are not only at half their projected strength but also often barely trained and ineffective.