It should be noted that probably the main reason Trump is so popular is because people think he can beat Hillary. She would absolutely demolish him. His polls against her are garbage. He ran away from one debate because he couldn't stand the heat, and he's threatening to run away from the remaining debates because he can't stand the heat. In the eyes of the Democratic base, he is a monster to a far greater degree that Obama is a monster in the eyes of the Republican base. Anti-Trump turnout would be off the charts. He has no attacks on Hillary since everything wrong she has done, he has done worse. Platoons of reliable constitutional conservatives will refuse to vote for him (I'm one of the them).

The silver lining of a Trump nomination is that the people who supported him will get a rude awakening after he gets obliterated and they start to rationalize why. They'll then clearly see how terrible of a person they supported.