What I think will happen:
Iran and the other members of the JCPOA will continue the agreement without us. Trump will reinstate financial sanctions but avoid any new oil sanctions. He will threaten European companies doing business with Iran but take very little meaningful action otherwise. Should be noted Iran does almost 10 times as much business with the Europeans than they do with America so our sanctions wont be all that painful. I don't think much changes outside of America's influence continuing to diminish. It'll take at least a decade to build back up the confidence Trump has eroded.
Which at this rate is never. As soon as we recovered from our country being ruined, somebody else is ruining it.
Once again, Putin and Russian government officials are laughing and toasting with shots of Vodka.
How easy it is to fool the idiocy-class in America, in electing an Orange Clown to lead, and bring our county (and relations with our allies) down.
Thank you trump cultists.