I agree with much of what you say here, I've just got a few little things to point out.
-Iran is not a theocracy. By definition, a theocracy is a government where (a) priest(s) rule in the name of god. While it does have some aspects of the very religious caliphate style governments, and while the entire government does have a very strong religious influence, by definition it is a flawed republic in which the supreme leader appoints those who appoint him (Effectively making him an autocrat, similar to Russia's upper parliamentary chamber being appointed by the President, which in turn appoints the prime minister, who appoints the president)
-China's economy is doing well. While yes, growth is slowing down, and they may not be headed for the position as superpower as previously thought, it is still growing by about 6%. Compare that to the U.S' 2%, an already strong figure, and you have a strong economy. Slowing economic growth is not an indicator of a weakening economy, as we can see with the EU, Japan, etc. You are totally right that they would be hesitant to intervene, however, as their military is still far from up to par with modern ones, and they need all the money they can get to continue to modernize it.
- We will never launch ICBMs at Iran unless they perform a nuclear strike first, which is currently impossible with their military technology. They, like all nuclear weapons, are simply a deterrent. ICBMs would serve no purpose if we were actually attacked, as any confrontation exceeding conventional military firepower would be apocalyptic regardless of what we do.
- If a draft is not necessary, or if the president is reelected, a proxy war is very much possible. Russia and China both fueled a proxy war in Vietnam, as both knew that they weren't actually risking a war with the U.S. (Mutually Assured Destruction, or M.A.D. for short, has been what defines diplomacy between nuclear adversaries since the dawn of the cold war).
I agree with the rest of what you say though. It would be foolish for Iran to attack the United States directly. It's in both our and Iran's best interests to de-escalate this, to prevent any further blood from being shed on either side. American or Iranian, a death is still a death regardless and if it can be avoided it should be.