Iranian government massacres its own civilians whenever they dare to demand change. Iranians are also largely secular compared to citizens of most Arab states, and hate their government. They're also mostly Shia, which makes it hard for likes of ISIS and Al Qaeda to gain ground there, as Shias are enemies to Sunni extremists.

I believe there's a much better change of democracy / sane regime in Iran, than there ever was in Iraq and other Arab states.