Saddam will be dead by early 2007.
As for the rest, Maliki doesn't need the U.S. anymore. He's got enough Shia backing, especially from the more heavily armed contingents, to remain in power. Remember, this is Iraq, not a conventional battlefield. U.S. airpower and logistics are nice, but they pale in comparison to having men on the streets enforcing your will the old fashioned way. Once he controls the Ministry of the Interior and the military, and has the backing of the militias, he's the top dog in Iraq. With U.S. forces out of the way, he'll be free to pacify the Sunnis the Iraqi way.
The Kurds, who have their own police and military, will happily turn a blind eye to the central government's smackdown of the Sunnis. Aside from a few suppressed chuckles, you won't hear a peep out of them. They'll keep Kurdistan quiet, while Maliki cleans the rest of the house.
Maliki's really not in that bad of a position, he's just constrained by the fact that he can't move a company sized element across the street without U.S. approval. Once he has a free hand, that hand will be b%&$@slapping the Sunnis into line, and hard.
The Saudis have already had a few things to say about that..namely, it won't happen. They are predominately Sunnis.
If we leave Iraq post haste..big brother Shiite (Iran) and big brother Sunni (Saudi Arabia)will have a loud disagreement in the former green zone. It won't be pretty. At the max..the US needs to standby in Iraq for now to be a referee. We had better be a fair and balanced one or somebody won't be happy. And we don't want anyone to be unhappy now do we? :)~(Barf)