Good post yours. At this point in time, I'd bet a good chunk of money that Trump will be the GOP nominee. But Trump vs. Hillary or Cruz vs. Hillary...I'd pass on either bet. A bit too close to call, for the reasons you mentioned.
As a side note, a Trump vs. Hillary match-up should result in a Trump landslide, much like a Reagan landslide. Trump will attract the blue-collar types, etc. But in Reagan's day the media was at least somewhat fair. Times have changed.
Trump will get 0% of the wetback vote and not much more of the New Citizen vote.