Trump will do far better in open primaries than Bush. People like to compare Trump to Perot, but they forget most of Perot's support came from independents and democrats. Trump will do very well among those voters, many of whom would never vote for a GOPe candidate, especially one named Bush.
Those primaries are a long way off, and I do think there’s a strong possibility Trump will self destruct. He does control a large part of the protest vote for the moment, but there are only so many protestors. You can imagine the moderate/centrists in blue states will rally to Jebbie just like they did for McCain and Romney.