My bad let me qualify it. If Iran doesn't get its nuclear weapons, then the West will force a regime change. If it does, then it might turn into a NK type stalemate.
Without nuclear deterrent Iran has not nearly enough military power or land mass to deter an invasion. The US military is light years beyond anything the Iran has in possession, both equipment wise and philosophy wise. Iran has a significantly more complicated geography than Iraq, but I'm confident that if military action does take place, the US will triumph. It might not as easy as taking Iraq, but it won't be much harder. The 2003 Iraq War is a bad example, but remember the first Gulf War where Iraq was still a mighty regional power with years of combat experience and high morale. There were many doubts as to the losses that NATO forces may have suffered before the action started, but the war concluded with minimal casualties and cemented the military dominance of the coalition forces.
The more difficult part would be to manufacture a reason to attack Iran, but I am also confident in the abilities of the US and its allies to pull that one off.
I don't agree with you. The US public has no stomach for an invasion of Iran. We don't want that. Iraq soured the West on grand foreign adventures and even if the US wanted to invade Iran it would never be able to get other nations to go along with it. Invading Iran would be the last problem on top of a stack of problems that broke the back of American world power, and that is understood in Washington. I'm sure there are people that would like to invade Iran but all except for the most foolish and unrealistic realize that even if it is technically possible it's not advisable.