Hossein Askari is pessimistic:
The nuclear issue is a popular policy. What the United States should say is we are going to impose sanctions until you hold free elections, respect human rights. … This would have much force within Iran and with a change in regime, then the nuclear issue could be better resolved. The issue the US has picked (the nuclear issue) will not rally the people against the regime. Sanctions are aimed at hurting the government and forcing the regime to change its policies, or squeezing the average citizen to turn against the regime. It hurts the average person. This is sad, but inevitable, fallout of sanctions that cannot be helped.
Dan Drezner counters:
[The US wants] the sanctions to be so crippling that Khamenei's ultimate authority comes under challenge, to the point where factional divisions open up space for a substantive change in the regime. This might work, but I'd put the odds of this happening at less than 1 in 3. Still, this is the thing about instances in which economic sanctions are deployed. Even if their prospects don't look great, they're usually employed because the other options have even worse odds.
For the next, say, six months, pursuing this course of action makes sense. It weakens Iran at a key moment in the Middle East, and it might lead to some positive developments down the road. That said, even if the sanctions work in crippling Iran's economy, they likely won't work at altering Iran's objectionable nuclewar policies — the expectations of future conflict are too great. At that point, the United States is going to need to consider whether its prepared to pursue a longer-term containment strategy or alter course.
Benjamin Friedman thinks the sanctions, together with other factors, have turned Iran into a containable paper tiger. Meir Javedanfar worries that economic pressure might cause Tehran to attack Israel.
The Dish 