The larger message here is that Mr. Ahmadinejad's and his boss, Supreme Leader Ali Khamenei, have no interest in a "grand bargain" with the United States or an accommodation with the Security Council. Sanctions have hurt the Iranian economy, but they have had no impact on the regime's belligerence. Iranian negotiators may eventually turn up in Geneva. But as long as these rulers are in power, Iran will not give up its ambition to exercise hegemony over the Middle East.
Sanctions are starting to bite a bit more. So I do think that it is a question of whether economic difficulties exert an impact on Iran's behavior for the better (hopefully by prompting a revolution that gives us a government we can deal with) before Iran gets nukes which will help instill enough fear to undermine sanctions.
The question from our point of view is whether there is time enough for Iran's mullahs to die. Iran wants time enough to kill.