"What about the following scenario, Dr. Wolff. Say Trump gets a wide majority of the delegates but not enough to pass the threshold number to secure the nomination. After some backroom dealing, the Republicans figure out a way to nominate Cruz, Rubio or Kasich instead. Disaffected, Trump decides to run as an independent. Meanwhile, Bernie loses to Hillary. Do you think Bernie would run as an independent against Hillary, if Trump runs as an independent?"
A word of caution about this sort of speculation. A number of states have "sore loser" ballot provisions, which forbid someone from running on a third line if he or she has appeared on one of the two main lines [Democratic or Republican] in the primary. It would be very difficult for Trump or Sanders to make a third/fourth party run.
However, if the party big wigs deny Trump the nomination at the Convention, I think he would probably walk out and call on all of his delegates to do likewise. It would be real chaos.
I think they are stuck. If Trump comes to the Convention with, let us say, 1100 delegates, and no one else has more than 600 or 700, it is just not realistic to think they can snatch the nomination from him.
I think the most likely scenario, if Trump doesn't make it to 1237, is that before the Convention he cuts a deal with one of the other candidates to trade the VP slot for his delegates.