Above all: Play the long game, because time, demographics and generational change aren't on the side of the current regime.Source: An Expert's Long View on Iran by Gerald F. Seib
It is my estimate that for the following reasons, the United States and Israel does not have the luxury of time as regards to Iran.
1. If this takes any longer, the nuclear capability of Iran improves with each passing time. We don't even know if they have a nuclear weapon already.
2. If you take a review of the personalities leading the fight against the present Iranian regime, some of them like Rafsanjani are hostile towards Israel.
3. The longer one waits the lesser the effectiveness of sanctions will be since you are giving the present Iranian regime, time to prepare for such an eventuality.
The strategy of replacing the regime will only work, if the US has a proper understanding of who will replace the present leadership. If the replacement will just echo the same hateful ideas by the present regime then it will become even more dangerous since it now has the support of the Iranian population!
A different view and ingenious solution is needed against Iran since this is a case not seen in history. If one thinks Iran is only after economic and political standing in the global scheme of things, the analysis is dead wrong and is a big risk to the United States and that of Israel.