I believe that Iran is serious about acquiring nuclear weapons. I also believe that much of their current posturing is just that....posturing to play for time.
What they don't realize is that the US, and more significantly, Israel must take their rhetoric seriously regardless of whether we believe that they are 3 months or 3 years from a nuke....neither can afford to be wrong - particularly Israel!!
So the bias must be for a strike earlier, rather than later. To my mind, that says Israel goes....we seem to be paralyzed with diplomacy....that we must know has no chance whatsoever of success!!
To the substance of your question: I think that after a conventional attack to disable Iran's nuclear and missile sites, Israel will make it clear that the hole card is nuclear and it is held in a clenched fist. That should do the trick.
Why? Because Iran doesn't have a hole card. And as attractive as the coming of the "Twelfth Imam" might be, I'm not sure how many nutty Mullahs would bet on it when the chips were lined up against them.