My guess is that the vast majority Sunnis are not whack jobs and just want to live in peace with their neighbors; and for that matter, the vast majority of Shiites could be described the same way. If some kind of deal can be struck so that both can cooperate to stop disaffected elements both inside and outside the government from taking advantage of the current situation, you'll see a marked improvement in Iraq.
The real problem is there are agitators on both sides backed by Iran and al-Qaeda that are doing everything they can to spark a civil war in Iraq.