BBC News - Iran 'not co-operating' says new IAEA chief
If Iran complies with all IAEA and UN requirements, its nuclear program, and therefore its commercial and economic development, will fall more under the influence of Western Powers. The upside for the world is that it will not develop its Nuclear military power.
If Iran does not comply and continues on it's current path it will face sanctions. I wouldn't be surprised if in the next couple of years America and a couple of it's friends start talking about an Invasion. Russia and China will say no of course and we'll have to see how that plays out.