*nods* What we're seeing is exactly what Haley played for. If Trump's campaign collapses, he dies or is disqualified from the ballots as a result of Fourteenth Amendment challenges, Haley is now in position to pick up the pieces.
Meanwhile, DeSantis chose to double down on beating Trump straight up. His problem was that as Trump supporters got to know him, they quit liking him, which in turn pushed away all the never-Trumpers who supported him only because he was the sole viable alternative at the time.