Looks like Iran is being allowed to withdraw to save face, very diplomatic. You are correct Iran has nothing to concede, they just have to get rid of the troublemakers then they will be fine.
http://dailycaller.com/2018/04/30/iran-deputy-foreign-minister-withdraw-nuclear-deal/
that article does not say that they pulled out of anything it says that the minister called the accord unsustainable in its current form. pulling out would have been worded differently and there would be official news/ proof not twitter banter...