This is just theater. With or without cooperation, western countries will rely on espionage to assess what Iran is doing with its nuclear program.
Iran was probably never fully transparent with the IAEA, and despite declaring everywhere that their nuclear program is "peaceful", they enriched uranium to levels far beyond what is necessary for power - while developing systems and mechanisms required for a nuclear bomb such as a massive ICBM industry and warhead R&D.
It is so blatantly obvious that Iran was doing this while trying to dupe the IAEA, that it somewhat reminds me of the martians from Mars Attacks who keep playing the "we come in peace" message while running around shooting lasers.
Hopefully Iran's facilities suffered enough damage to create new opportunities.