An agreement to restore the 2015 U.S.-Iran nuclear deal is unlikely as imminent as EU diplomats have suggested due to Iran's continued demands for sweeping U.S. assurances. But even if Tehran secures an agreement that guarantees widespread sanctions relief, Iran's structural economic weaknesses will continue to deter foreign investment. European officials recently expressed hope that Iran and the United States may be closer to restoring their beleaguered nuclear deal -- known formally as the Joint Comprehensive Plan of Action (JCPOA) -- than they have been in months, with EU foreign policy chief Josep Borrell noting on Aug. 22 that a meeting in Vienna could take place as early as this week. But on Aug. 15, just a week after the European Union proposed its ''final'' version of a draft text to revive the JCPOA, Iran renewed its demands for ''sanctions guarantees,'' which has jeopardized the prospect of a deal being...