Well, we sanctioned Iraq for 10 years with little effect beyond keeping Saddam from slaughtering the Kurds and Shiites. Iran isn't a truly authoritarian country though... power is held exclusively by a cabal of religious leaders, but those leaders are individuals that respect one another enough to catch each others' mistakes, and have already put down dozens of revolutionary movements by reliably recognizing them before they grow large enough to present any real threat, using their insiders' knowledge of Khomeni's original revolution and how it could have been stopped.

There won't be any internal change, and sanctions are unlikely to protect their democracy movements, or even slow their efforts to develop nuclear weapons. They'll just sell the food and medicine that the sanctions don't apply to for weapons and equipment, same as Saddam did, both starving their people to win the propaganda war and stockpiling ammo to put up a fight when the shooting war begins.

True, like I said I'm not holding out a helluva lot of hope that this will work. That said, I can't recall any time when the Iraqis made genuine trouble for Saddam after he smashed the uprisings after the 91 war. The Iranians have shown their willingness to protest. I just don't know if it'll do any good.