It's not gonna happen. There are so many elements that make it a terrible idea. People are still pissed about Iraq, Afghanistan, and Syria. It would ruin our world image probably irreparably. Iran is bigger, richer, and stronger than Iraq. If Iraq was a quagmire, Iran is a bottomless pit of quicksand. Chances are China, Russia, and half the countries in the European Union have their own interests in Iran. Starting shit in Iran wouldn't be throwing gas onto the fire, it'd be driving a fucking tanker truck into it. It would be so stupid and crazy that saner minds in the American government, the American Military, and the global community would do everything in their power to stop it.
In sort, there are so many reasons why it shouldn't happen, there's no way that it could happen.