Vice President Vance said many nice things about "progress" with Iran as he led the negotiations that ultimately failed. SecState Rubio kept quiet. In picking one of the two as a presidential nominee in 2028, who do you think came out better? It is Rubio, is it not?
Vance took a risk, likely at Trump's insistence, and it failed. Trump now bad mouths Iran, after saying quite a few positive things himself. But Trump can't run again, so his comments are old news, not relevant to 2028.
Basically, I think Trump threw Vance under the bus, figuring he was disposable. Trust Trump to find a use for a Vice President, something many presidents never quite manage, certainly Biden didn't.
In my judgment, Rubio is talented, smart and tough. I hope to be able to vote for him a couple of years from now. Caveat: two years is an eternity in politics, my opinion may change.