I wrote "containment for a while"
The US will need a much larger force if the decision is made to occupy Iran until a "nicer to the US" government is installed....
I have a feeling you will not see in Iran what we have done in Iraq. My guess is you will see some very nice bombing runs from a 1000's of feet in the air which will take out some very key installations.
I don't think so; occupation won't be necessary, as the Iranian people are poised to take back their government if we do what we need to do.