I think they have written off FL. NC is proportional, but no matter. The “expert”’s point was that the party needs to keep all the opponents in play, and nibble at the delegates in all the states that are not winner take all. The problem is that it will be obvious that Rubio and Kasich can’t win, so their ONLY purpose for staying in would be to block Trump. It would be deliberate disunity.
Yet they'll do it. They are not going to back off.