My own perspective is the pub party has already blown up. Trump is not a byproduct of the f**k it wing of the party. He is the product of voters against the establishment wing of the party that has lied to the American public for 20 years. They have held the party together with the pledge of lower taxes, border security, and social conservatism. They have delivered on none of these promises and exploded the federal deficit. Though unimportant to me, I think social conservatism has been the most important glue to hold the party together for the past 35 years. This is the Cruz section of the party you spoke of in your post. The pubs won't exist if this is all that is left of the party next year.
It's is going to be interesting to see what happens over the next few years. The dems basically threw the conservatives out of the party in the late 60s and appear to be doing the same with moderates today. They are so close to becoming a socialist party. I believe their existence as a viable party is due to the complete disregard of the republican establishment.
It seems the majority of the American people are disenchanted with both the dems and pubs. I don't believe for a minute that Trump is purely Republican based. I believe, like you, he is getting a lot of crossover support. Perot almost pulled off a third party in the 90s. Trump may be on the verge of accomplishing that goal today.