” If Trump doesn’t get the nomination, his supporters will stay home.”
I don’t think that’s true. Who did Trump supporters support before Trump? They will go back to that candidate. What Trump brings to the race is something unlike Romney or McLame brought to their races, conservative support. If Rubio won the nomination I would probably stay home since I already had that in 2008 and 2012. If Trump wins the nomination, I am voting for him, even though I am a Cruz supporter.
Not according to a lot of Trump supporters on this forum. They have openly said if Trump does not get the nomination or goes independent, they will vote for him or stay home. And then they jump all over anyone who says they will vote 3rd part or stay home if Trump DOES get the nomination. Now, not all of them say they will do that, but a significant number of them do.