Idle speculation from a counterintelligence officer.
1) Go back to Trump’s recent past, you see he is buddies with the Clintons, especially Hillary. He has given money to their foundation and he was once a big fan of of Hill’s views on immigration reform. With his background, he’s a really a Demo in Repub drag covertly sullying and tainting the Republican BRAND both by endless accusatory charges against individual Repub elites and by embodying in his person and message – in a very exaggerated way – the worst and ugliest dark shadows looming behind the Repub agenda. When people look at and listen to him, he implicitly reminds voters – in his very own personal example – that Repub pols are racist and way too rich to care about anybody but the rich, plus profoundly hypocritical, indifferent to the facts, etc. When they see/hear him hurl bitter accusations against other Repubs, he reminds them explicitly, like a Demo might, that Repub pols are are incompetent, hypocrites (e.g., not caring for vets), and religious nutjobs. He makes them look bad in his personal example AND what he directly says about them. Objective of this two-pronged approach: get enough people to be revolted by the sheer unattractiveness – on all levels – of Repub pols to vote Demo instead. Bingo, Hill wins. Likelihood: High.
2) Trump does not give a bleap about getting approval from the Repub High Command – he’s a rebel oligarch warring against Republican oligarchs. The very consistent and even personal nastiness of his attacks on them (e.g., McCain) show he wants to topple and undermine and replace them with his own form of oligarchy. His constituency are white lower middle-class and deeply alienated prols, both men and women, but especially men. Such people look at the Repub mainstream oligarch fat cats and are repulsed, having no way of identifying with them. Trump – he’s rough, hard around the edges, gives not a damn about the polite ways of rich oligarchs, a lot like the prols and poor whites themselves. He’s someone, though very rich, they can identify with and thus, vote for. Likelihood: Medium.