This is completely different from iraq. i hope you have seen the IAEA report which clearly states that iran is weaponizing it's nuclear program. it's not only the CIA but israeli, french, british and others intelligence services that confirmed this. sheekada way ku cadaatay iran.
i believe arabs more than anyone else including israel will be pushing and rooting for an attack on iran, they have most to lose. america has said it will not tolerate nuclear iran for it's security interests in middle east i.e energy and israel will not allow hezbollah to have nuclear umbrella and blackmail them from the north.
if it did happen and the americans and israelis plus whoever else joins only attack without deploying troops on iranian soil then it is easily won. iran will still be massively outgunned. the reprisals might come in the form of terrorism. but for them to close hormuz will be suicide on their part. all in all despite the crazy rhetoric i think iran will be contained easily. so WW3 is off.