this is the moment for which conservatives have been preparing for the last year and a half: sustaining the illusion of "victory" just long enough to be able to blame Democrats for "losing Iraq" when things go wrong. Get ready.
He's right, of course. The faction fights and social cracks in Iraq pretty much guarantee more violence at some point and it won't matter a damn how many US troops (or even whether there are any at all) are there or not when the next outbreak of Iraq's cyclical boodfeud hits. It might be Kurds vs Shia, Shia vs Sunni, Sunni "Sons" vs Sunni Iraqi Islamic Party or Shia Sadrists vs Shia Badrists - but it won't matter a damn to Republicans that all Bush and Petraeus ever did was paper lightly over those cracks, only enough to bring Iraqi violence down to a per-capita equivalent of a 9/11 a week. It's still true that the US needs to withdraw before those feuds that Bush blew the lid off by invading can finally resolve themselves and it's still true that, for pro-occupation conservative pundits, it'll still be Obama's fault.
(Even if the Iraqi leadership wants the US to leave.)