I agree with some of PanzerJaeger's analysis but not the conclusion. To the extent that the insurgency is devolving into a Sunni rebellion, I wonder if it is possible to defuse it by greater decentralisation - rather than civil war? Give the Sunnis greater autonomy - make Iraq into a Belgium - and you might reduce their willingness to align with al-Zarqawi and fellow Jihadis.
But I do agree that getting the Iraqi security forces to fight the insurgency is probably better than relying on the Coalition troops. It makes it harder to portray the insurgency as an nationalist/anti-Western struggle and again should help isolate the hardcore.
Bookmarks