Seems more wishful thinking, and then they try to back it up with various theories.
Anything can happen in political races, and Trump could lose to Bush, Carson or Cruz. However I just don’t see Trump simply getting bored and dropping out. He is enjoying this run way too much. What else can he conquer at age 69? More money, more fame? Beautiful women? He already has all that.
You’re right. Anything can, and often does, happen. However, losing to Bush sounds possible only if a major portion of the Republican primary voters take massive doses of Prozac with a side of Valium. ;-)