Came across two online articles today, loosely related.
The first was indicating that Trump's campaign was meant only to send a message, to shake things up, and that he never expected to get the nomination. Now that he actually has it, he's facing an "oh, ****!" moment, but his ego is far too big to admit it or back down. This would kind of confirm my suspicion months ago that i wasn't sure if Trump really wanted to be President.
The second is that the GOP is looking into how to handle a situation in which Trump withdraws from the election between now and November.