Agreement can survive without US
The agreement could be maintained in a watered-down form even without the US, former French ambassador to Iran François Nicoullaud writes in Le Monde:
“What can the Europeans do? They've already expressed their intention of maintaining the Vienna agreement should the Americans pull out. Russia and China would follow suit and so will the Iranians too no doubt, so as not to forego the advantages gained when the sanctions were lifted. So the deal could remain in place regardless. The new US sanctions would be more of a nuisance than before, it's true, because with globalisation the Americans have discovered that even without extraterritoriality clauses they can impose sanctions on foreign firms with financial interests in the US, or which make use of the American financial system. But no doubt ways around this can be found.”
Didn't Trump want to be a deal maker?
If the US proves to be an unreliable partner by pulling out of the Iran agreement any future peace talks with Pyongyang are likely to suffer as a result, News.bg predicts:
“The potential withdrawal of the US from the nuclear deal will have a negative impact on the North Korea crisis. Kim Jong-un's regime will be less motivated to conduct a dialoge if it knows that the US could change its mind at any moment and renege on its part of the deal. ... Donald Trump needs to be reminded that during last year's election campaign he promised to be a deal maker, not a deal breaker.”