Nobody, not even Condi Rice, wanted to speculate about any Plan B.
First, invade a beaten, sanction-starved and bombed-out country that happens to be sitting on the third largest oil reserve in the world, and then grab the oil fields, while letting everything else descend into chaos.
“Stuff happens” says Don Rumsfeld.
Then disband the Iraqi army and the police force, who might have been able to keep law and order in the chaotic situation, and then institute CPA order #17 which states that US military personnel and contractors can not be prosecuted under Iraqi law for crimes they commit.
Then maintain the conditions for mass sectarian killings, low grade civil war, mass refugee movements, and further chaos everywhere. Let the local militias do whatever they want in their areas of influence.
Then tell the American public on the TV that a continued heavy-handed military occupation of Iraq is essential to quell the same violence caused by the invasion and draconian occupation of Iraq. Tell the American people with a straight face that leaving Iraq will result in the very same problems that invading Iraq caused.
Turn an oil-rich country into cauldron of death so that you have an excuse to stay there forever with your military. Cause all the death and destruction, and then warn that the obvious solution - ending the military occupation - will make the chaos you caused worse. This is akin to stepping on a hornets nest, but then refusing to back away from the swarm of stinging hornets because moving away will make the hornets angrier… “they might follow you home”.
Once you have made a total mess of Iraq, and allowed sectarian killing and mass displacement to go unchecked for years, then you could threaten to repeat the entire process in Iran to ensure you have an endless excuse to keep your military in the region… right near the oil.
So when someone asks you, “why would they consider something so crazy as bombing Iran?” You can reply “Plan A friend, Plan A”.