Well I don't mean an American-led "freedom" revolution. I mean the people need to rise up against the mullahs and do to them what they did to the regime before them.
They tried that recently. Sadly it ended with many students in prison :(
Unfortunately Iran is going to have to go through a slow revolution. Where the elders die off and the young take power. In some ways this is better than a Big Bang revolution like we want - it lets them gradually establish the system they want. Even if it's not the system we wish they had.