The nucleair business/trade is worth hunderds of billions, imagine Iran having a 10% share in this growing sector.
The main reason that they want to exclude Iran is this, they don't want new rivals in strategic industries. Iran will and should NEVER being excluded from this club.
It is worth that much, but Iran can never have a share of that market for several reasons:
1. Iran needs to increase its enrichment capacity to over 1 million SWU/year to export enriched uranium. We need 600,000 SWU UF6/year for our nuclear reactors until 2030, if we do not build new reactors. Big actors in the market are way above that enrichment capacity, usually over 5 million SWU/year, or even 10 million SWU/year. Since Iran uses SWU UF6/year, you should multiple those numbers by 1.6 as well. Obviously, not only we do not have enough centrifuges to reach those numbers, and Fordow and Natanz currently cannot host more than 100,000 centrifuges, the world will not allow Iran to reach such a huge enrichment capacity.
2. Even if we reach those numbers, and we somehow circumvent sanctions that they will all place on us, we will need to provide electricity to our centrifuges. We are talking about tens of gigawatts-hour of electricity for 1-5 million SWU. As long as we have electricity shortage in Iran, we cannot be a major export of LEU.
3. We do not have enough natural uranium in Iran to export 100 tones of LEU per year. Most light-water reactors consume over 20 tones of LEU per year. We do not have that much uranium in Iran to export large quantities of LEU to foreign countries. In fact, our uranium reserves are barely enough to support our own needs for the next 30-40 years.
4. The issue of branding and the fact that most countries with nuclear technology, now or in future, will be US/West allies and will not approach us when they have better options with better branding.
I think the main issue with the US proposal is that they have offered nothing in return for such huge demands. They haven't offered a complete, immediate lift of sanctions, passed as a law in the US. They are talking about step-by-step lift of sanctions, which is not only stupid, but has already been tried and failed. They haven't offered normalization of ties. Their offer is quite one-sided and delusional. I think the negotiations are over and we should prepare for the other scenario.