Do yourself a favor and read it.  These are the closing paragraphs, but the support for his argument preceeds it:

Therefore, I conclude that the United States is stuck in Iraq for the medium term, and perhaps for the long term. The guerrilla war is likely to go on a decade to 15 years. Given the basic facts, of capable, trained and numerous guerrillas, public support for them from Sunnis, access to funding and munitions, increasing civil turmoil, and a relatively small and culturally poorly equipped US military force opposing them, led by a poorly informed and strategically clueless commander-in-chief who has made himself internationally unpopular, there is no near-term solution.

In the long run, say 15 years, the Iraqi Sunnis will probably do as the Lebanese Maronites did, and finally admit that they just cannot remain in control of the country and will have to compromise. That is, if there is still an Iraq at that point.