The Arab Spring was going to happen eventually. The "secularist" governments of the Arab world were always horrible. Nobody wants to live under the likes of them. But one of the problems with governments who love killing and torturing people to stay in power is that generally the people most likely to fight them are either desperate or insane. Laugh about the 72 virgins all you like, but there's a reason Islamists are willing to endure having a member of the Republican guard burn every inch of their gums before they reenact A Serbian Film on their ass. Moderate people don't wanna have a quick death be their best option.
The only thing I can see changing is a civil war where Saddam Hussein, or one of his sons, is commander of one of the armies: Followed by a horrific purge enacted by whoever wins the conflict.
It was definitely a mistake to leave Iraq hanging. We'd made serious progress, and flushed it all away for short term gain.