This is probably just another of Irans famous delaying tactics. We sit down have a summit, talk a little, don't reach an agreement. Iran cannot give up its nuclear program because they need nukles to achieve their long term political & military goals. They want to be the new regional superpower, they are spending huge amounts of money on their conventional forces & missile program including the development of ICBMS. They want to be able to bully the arabs in the Gulf and dictate terms, they can dictate to the Americans .. already they are demanding the US leave the Gulf making threats about how they can sink US warships. With the nukes Iran thinks they can push the US around and dictate Middle East policy thinking that if Iran has nukes America will never dare mess around with them and so will be more willing to agree to do deals on Irans terms. Its also about prestige especially in the islamic world .. a muslim nation has nukes. Iran wants to be a global power and be able to push everybody around including the US and the only way they can ever achieve those goals is with nukes, they know conventional weapons alone will only make them a local force and its not hard for their neighbors to buy more conventional weapons to match them. There is no way diplomacy will ever end their nuclear ambitions, without the nukes Iran is just another Middle Eastern country with them its a global power especially if they have the oil which they also see as a weapon to be used for blackmail. Assuming a deal was reached it might slow things down but the desire for nukes would continue we also don't know for sure how much material they have enriched by now so they may already have enough for a bomb and they just wont declare the existence of this material so it would limit any damages of any deals they might do to stall things but unless their infastructure is destroyed it is only a matter of time before Iran gets nukes and the US & Europe will be to blame because they knew what was going on but turned a blind eye so they would be under no pressure to use military force.
Brazilian head of UN peacekeeping force in Haiti dies of heart attack (Reuters)
from the article: Iran says three-way summit could finalize nuclear deal with West