First, Trump very few actual principles, which makes it easy for him to make complete reversals of his prior positions.
Second, Trump has fallen out with old guard neo-cons like John Bolton. Bolton is extremely hostile to Iran and was Trump's national security advisor. After he left the Trump administration, he has become a harsh critic of Trump, calling him "unfit" to be president. Without Bolton and his cohort, there will not be the same anti-Iranian whispers in his ear.
Third, Russia is now an ally of Iran. If Putin is friends with someone, Trump is more likely to go along.
Fourth, the Saudis hostility towards Iran is less severe than it was in his first term. Saudi Arabia is not as influential on Trump as Russia is, but it is another dictatorial regime that has learned how to manipulate Trump. While the Saudis won't necessarily push him to reconcile with Tehran, they are likely to be less hostile to the idea than they were between 2017 and 2020.
Fifth, there is no agreement with Iran with any opponent's (Obama or Biden's) fingerprints for Trump to be hostile about.
Sixth, Trump really wants to be a peacemaker in the middle east. He claimed he could do it, and that's a lot harder to do without involving Iran.
The only major impediments I see to Trump improving relations with Iran is the Israelis will hate the idea, and because Iran was so thoroughly demonized in the U.S. in the 1970s and 1980s (when Trump seems to have formed his opinion about most things). But if Iran butters him up enough, I don't think that stuff will really matter. Hell, I bet Iranians can get sanction relief if they just let Trump build a Trump Tower in Tehran.
