my feeling is that that is not the way this sucker is going to unfold. the way this sucker is going to unfold is that israel is going to bomb iran. soon. the only hesitancy, i assume, would be that it will strain relations further between israel and the obama admin. but there will also be an element of the american government that more or less implicitly supports such a move. also, no american administration can simply unequivocally condemn any aspect of israel's policies. i feel, offhand, that unless iran does actually already possess nuclear weapons (which i don't think they do, but who knows?) iran cannot project real military power in israel's direction, though there is liable to be some retaliation.
the result of an israeli strike are of course impinderable. obviously, regime change cannot be accomplished by foreign powers. an israeli strike is likely to strengthen ahmadinejad's hand (and that of whatever portion of the clerical hierarchy is on a's side). but there might also be a slow disintegration of the theocracy, if their impotence is really demonstrated. if iran were in a position to go to war with israel, a goodly portion of the world might be embroiled in the confrontation eventually. the tensions between "islam" and "the west" might be ratcheted up to almost unbelievable levels. there might be renewed waves of terrorism etc.
then, of course, the end of the world, which i hope you are looking forward to as much as i am. the world, and in particular our species, has persisted far beyond its worth or interestingness, as i understand again every time ahmadinejad addresses the un.