In my opinion, the worst case scenario is an arm race between Shia and Sunni muslim countries, if Iran get nuclear capacity. Teheran and the clerc regime, also knows that any nuclear attack against Israel, will end Persia's 6 000 yrs + long history. The best solution would be to make Iran a sensible country and include it into the world, after the regime has gone. It will take time, but it is possible. Iran has an demographic time bomb that sooner than later will shake that country. Only to hope that the Great Persian culture can continue as a trusted member of the world society. In the mean time; trust your neighbour and keep your gun powder dry :-))).
Jerusalem suburb of Even Sapir evacuated as wildfire spreads (Haaretz)
from the article: Iran Defense Minister: Israeli strike would be a suicide mission