If the treaty is dead, the US struck the mortal blow-- and accomplished nothing but the nuclear proliferation of its enemy. And for what? Sabre-rattling?
1) Wrecking a treaty Obama had a big hand in, because fuck Obama and everything he did.
2) Because the USA is now Israel's and Saudi Arabia's hired thug in lieu of having its own independent foreign policy
3) Just to maintain a "useful enemy" for domestic politics posturing and rhetoric.
Scrapping the JCPOA seems to me replacing a potentially useful plan with literally no plan at all, just a holding pattern of pointless antagonism. I am totally unclear what advantage the USA's sanctions are
for the USA over Iran. The USA has already tried pressuring Iran with sanctions: it failed last time and it will fail now. A "boots on the ground" military action is a non-starter. It can try bombing it into the stone age for... I have no idea what, except the satisfaction of Israel and the Saudis.
I think it should engage constructively with Iran. Iran is partly troublesome partly out of ambition, but partly out of insecurity that an Arab alliance, plus backing from the USA, is a threat to it (Iraq-Iran war and all) - plus of course the concern over Israeli nukes. At some point, I suspect what Iran wants is in large part guarantees
of its own security. If it gets them, it will be less inclined invest so heavily in its own, both in terms of weaponry and funding violence across the Middle East and in the long run tensions might just drain away anyway. There's a big fog of distrust to grope through, but I don't see why it's not possible.