Mediaboss Marketing

To be sure, the United States and Iran remain divided on a number of major political issuesincluding Iran's support for Syria's leadership, and perhaps especially its refusal to recognize the state of Israel. Iran has also directed extremely threatening language toward Israel, a critical U.S. ally.

Aside from Israel, U.S. allies Saudi Arabia and the United Arab Emirates would become concerned by renewed relations between the United States and Iran. Saudi Arabia has remained the top U.S. ally in the region (besides Israel) because it has provided abundant oil and cooperated with American military activities in the region, Bremmer said. But that relationship may be no more of a natural fit than a relationship with Iran.

"These are strategic allies of convenience, but there's not a lot that really binds them together," Bremmer said.

Read MoreWithout a deal, Iran's economy to be on 'its knees'

American and European financial institutions and companies would be hesitant to do business in Iran in a post-sanctions world, Clawson said.

Corruption remains a serious problem, and foreign businesses see the issue as having become even more thoroughly entrenched in recent years as Iran has had to devise ways to evade sanctions, Clawson said. The Revolutionary Guards, a politically powerful branch of the Iranian military, has a tendency to muscle into markets after merchants make them profitable, making it difficult to determine which sectors are truly private, he added.

Clawson also anticipates banks will be wary of running afoul of regulators following Commerzbank's anticipated $1 billion settlement with the U.S. Justice Department on charges that it violated Iranian sanctions and money laundering laws. Standard Chartered paid $327 million to settle similar claims two years ago.

Read MoreIraq's Kurdistan says to deepen ties with Iran

Ultimately, the United States has a broader incentive for rapprochement with Tehran. Iran has the potential to present a model for what world trade and globalization can bring to the Middle East, said Salehi-Isfahani. By playing the development game, Iran could influence its neighbors to do the same.

"This idea that you behave yourself, you have elections, you elect moderate leaders, you build your roads and schools, and you succeed, that's a lesson that Americans are trying to sell to the world," he said. "If Americans have any role in making that happen [in Iran], that will be the most stabilizing influence in the Middle East of anything I can see the Americans doing."

More here:
US and Iran could become, well, BFFs...really