@CalamityJane,
My argument, CJ, is that he is, so far. His first step is the nomination and in this he's been proceeding very successfully. His theory, according to all the sources I refer to, is that if he (or anyone else) can get all the conservative voters out to the polls, then there'll be enough votes for him to win. Movement conservatives believe this thesis even if, for example, Karl Rove does not.
He does have obstacles. And if he is the candidate, much will be publicized regarding what he has said before and what his father has said, etc. And it's clear that establishment GOPers do not want him to succeed, believing it will be a catastrophe as they believe a Trump candidacy would be. But as I noted this morning, it looks like Mary Matalin is now doing support for him and she's pretty establishment.
If you haven't, you should read Josh Marshall's take
http://talkingpointsmemo.com/edblog/i-think-it-could-be-trump
You might have it right. It may be that because I deem the fellow a sociopath (I'm not exaggerating) he scares the hell out of me.