"Pretty bleak assessment but probable accurate."
I think it is overly bleak, though I agree this is the path we must need be on. We hold more cards than many think:
1) If we hit the Iranian gas refineries, it will cripple Iran's defenses within weeks.
2) No need for ground invasion , we only need to bottle them up.
3) We would need to eliminate the Iranian air force, and navy if we took on the nuclear sites. But this is fairly conventional warfare and it would be hard for Iran to recover its military infrastructure. The Straits of Hormuz could be taken out of the equation.
Of course, this requires total conventional warfare, more in the WWII tradition. Think of the bombing of Germany without an invasion.