Why assume he won’t run again? it’s not like he’s just going to peacefully go away, and his supporters will be all riled up as long as Hillary is president.
The most telling thing so far about many of his supporters was crystallized for me when CNN interviewed some Trump supporters who COULD NOT BELIEVE Obama was campaigning for Clinton. They wondered why “no on is talking about a sitting president campaigning for a candidate.” Even after the interviewer told them all presidents have done that, specifically pointing out Reagan campaigning for Bush, they absolutely refused to believe it. The short-sighted, willful ignorance is really the scariest part of all this.