We will not do a major land incursion into Iran. It is a country the size of Alaska with a population of nearly 100,000 million. Based on the Balkans (successful) and Iraq (barely so) just a peace enforcement mission would require four or five divisions. We already have a 12 division mission for a ten division force. Even if we decided to do it, it would take at least six-months to assemble such a multi-corps land force in the Gulf. There has not been an iota of preparation for such an action.
We did not have air superiority over Vietnam. Over the North, where all the logistics and manpower originated after 68, the air was contested to the very end of the conflict. Hence our severe losses.
It will be interesting to see if some sort of culmination can be achieved by air alone. It has not been successful in the past, but in spite of Trump's rather confusing, "unconditional surrender" demand, the actual bar seems pretty low and perhaps achievable. Give up your nuclear program, cease production of long range missiles, and end support to regional proxies.
I personally think the most likely power to supplant the government is the Iranian Army. It is separate from the RGC and has chaffed under its control since the foundation of the Islamic State. The Kurds will be a geographically isolated complication for the regime.