At this point it looks like there are two schools of thought of what will happen now that the U.S. is violating the JCPOA (aka "the Iran nuclear deal").
First, there is the view that this spells the effective end of JCPOA and Iran will now be free to pursue a nuclear weapon without the inspection regime (whether or not they do so is a different matter).
Second, there is the view that I expressed below that the JCPOA can continue without the U.S. Iran and the other five parties to the agreement could continue to follow it. While the U.S. will impose sanctions, the EU, Russia and China will not (citing the fact that under the agreement those sanctions only go into effect if Iran violates the deal and Iran has not violated the deal). Whether this can work depends on whether Iran thinks it is in its interest to allow the inspections to continue despite the return of U.S. sanctions.
Iran does not do much business with the U.S. or American companies, so the only real effect of U.S. sanctions will be the effectiveness of the secondary sanctions--that is sanctions against foreign companies that do business in the U.S. and then also do business in Iran. Those sanctions would keep big multinational companies out of Iran. The U.S. has a bigger richer economy than Iran and if given the choice between having access to the U.S. or Iranian markets, most companies would ditch Iran. But that means that there would still be opportunities for smaller European, Russian, or Chinese companies that are set up just to do business in Iran. It might also be possible for multinationals to disguise their presence in Iran through a series of shell companies. If that happens, then the deal could survive without the U.S. while also shutting American companies out of the Iranian markets.
First, there is the view that this spells the effective end of JCPOA and Iran will now be free to pursue a nuclear weapon without the inspection regime (whether or not they do so is a different matter).
Second, there is the view that I expressed below that the JCPOA can continue without the U.S. Iran and the other five parties to the agreement could continue to follow it. While the U.S. will impose sanctions, the EU, Russia and China will not (citing the fact that under the agreement those sanctions only go into effect if Iran violates the deal and Iran has not violated the deal). Whether this can work depends on whether Iran thinks it is in its interest to allow the inspections to continue despite the return of U.S. sanctions.
Iran does not do much business with the U.S. or American companies, so the only real effect of U.S. sanctions will be the effectiveness of the secondary sanctions--that is sanctions against foreign companies that do business in the U.S. and then also do business in Iran. Those sanctions would keep big multinational companies out of Iran. The U.S. has a bigger richer economy than Iran and if given the choice between having access to the U.S. or Iranian markets, most companies would ditch Iran. But that means that there would still be opportunities for smaller European, Russian, or Chinese companies that are set up just to do business in Iran. It might also be possible for multinationals to disguise their presence in Iran through a series of shell companies. If that happens, then the deal could survive without the U.S. while also shutting American companies out of the Iranian markets.