It wouldn't surprise me if Trump (via Vance) secretly agrees to most or all of the Iranian demands and then presents to the media a list of fake US demands that he falsely claims Iran agreed to, and then has Fox and other right-wing outlets present it all as a great triumph for him (and it will be all him, not Vance). And in reality Iran will be quietly handed control of the Persian Gulf and allowed to charge fees for using the Strait, and Trump 2.0 will engage in mock outrage over Iran doing what it wants in the Gulf while we do nothing to stop them. Trump isn't smart enough to think up something like that, but a number of his minions are.
And if somehow things go wrong then Vance will become the scapegoat for agreeing to Iran's demands.