[[ Let Iran or somebody else miscalculate and strike us, and it would change. ]]
Things would sure change, you're right about that.
But I sense they wouldn't change the way you're thinking they might.
Let's just suppose, for the sake of argument, that Iran smuggled a couple of nukes into the US, and detonated them in major cities (New York and DC come to mind as the prime targets).
If this happened, you'd probably see at least 40% of the population, maybe more, call for "accommodation" to Iranian demands. And perhaps a sizable portion of that 40% ready to surrender outright, if it would bring "peace", and if it meant that we did not have to go to war.
If, after such an attack, the Iranian demand was that the USA "convert" to islam, I'd reckon 30% or more of the population would swallow that.
Sorry to be cynical. But we live in dangerous, changing times. I don't have a lot of faith that Americans are willing or able to "do the right thing" any more...