It likely would be illogical to expect Iran to fulfill the nuclear treaty's obligations

If you look at Iran's position as 165 million Shiite Muslims versus 1.1 billion Sunni Muslims arrayed against them there ONLY alternative likely is to develop a nuclear weapon in order to survive the Shia Sunni Divide and "World Sectarian WAr" between Shiites and Sunnis at present. The primary group fighting them is ISIS but Al Qaeda also is against them. But, long term unless they have nuclear weapons they just aren't going to survive the next 30 years. So, even though they might agree to this nuclear treaty I wouldn't expect them to honor it more than 1 to 5 years at most. And even then, likely they are going to try to develop nuclear weapons on the sly and to keep it out of nuclear inspectors prying eyes. Imagine if you were trying to survive as a minority religion in the Middle East and what you would have to do to survive ongoing and to be sure you would survive ongoing.