Without electricity, there is no modern life. There is no ability to communicate, run a financial economy, pay salaries, etc. Without fuel, there are no logistics; there is no capability to transport an army. Nor is there an ability to transport food; it would cause an enormous civilian crisis, and this would cause massive riots.
Iran would collapse, within a week. It would devolve into factions, and a civil war would start, similar to in Syria.
The US and Israel have been sitting on this card the entire time. They don't want to do it, because it would cause near permanent economic damage to Iran.
