Start with a probable assumption: The Islamic Republic will soon be able to produce a nuclear weapon whenever the supreme leader decides to do so. A new atomic accord, currently being negotiated in Vienna, won’t change the fundamental atomic fact: Biden’s deal undoubtedly will leave in place Tehran’s progress with high-speed centrifuges and a loose inspection regime that doesn’t account for, let alone eliminate, Iran’s ample stockpile of the high-tech components and maraging steel needed for the production of advanced centrifuges. Removing Iranian surpluses of highly enriched uranium by allowing its export abroad to Russia—an embarrassing destination now for the White House and the Europeans—or to China doesn’t really matter so long as advanced centrifuges can produce bomb fuel quickly. Iran’s nuclear engineers have shown that they can build high-speed, sufficiently reliable, machines rapidly.
Barring a great, felicitous surprise, the theocracy, which has clandestinely and overtly striven at great expense to develop the bomb since the 1980s, will have its nuke. Which brings up the question of what a post-nuke Iran policy would look like—assuming those who still want America to confront the clerical regime are in power with sufficient will and means to do something more than sanctions.
See also: Without The Iran Nuclear Deal, War Is On The Horizon