Drezner holds court on the question:
[S]anctions, on their own, will not lead to a regime change in Iran. Over the past five years this regime has made it pretty clear what it is willing to do to stay in power. That trumps any ratcheting up of the sanctions. Economic coercion imposes some serious economic costs on the regime, which is why they’re willing to talk about a nuclear deal. But that’s a tangible negotiation. Regime change is more existential threat, and if that’s the goal of the sanctions, then the sanctions will fail and fail spectacularly.
Larison agrees:
Because there is no significant political force in Iran that is willing to agree to maximalist hawkish demands on the nuclear issue, even successful regime change would not “solve” the nuclear issue to their satisfaction, because in the end the maximalist hawkish objection is to Iran’s role as a regional power.
The Dish 