The only way they would work is if the people took up arms and military units defected, like in Syria and Libya. This would most likely happen if there was mass bloodshed like what has been going on there. There would a civil war situation. Just as Gaddafi heavily relied on loyal militias, the ayatollahs would heavily rely on the Revolutionary Guard to crush the uprising. The opposition might need Western support and weapons, though. Likely a government dominated by Mir-Hossein Mousavi. He may be a reformist, but he is an admirer of the ayatollahs, so no normalization with Israel or the West. If, however, Mousavi is killed and/or some Iranian opposition leaders more sympathetic take charge, we can see them try to normalize relations and cut off Hezbollah and Iraqi Shiites from Tehran's payroll, though I'm not sure how the Iranian people would react. If the reformists try to build up and secularize the country, we might see Iranians in exile start to return and help build it up.