There is a serious danger that the GOP faces and which could turn into a political catastrophe. This would be triggered by the entry of a third candidate standing to the left of Trump and quite close to Hillary.
The doomsday scenario is this:
Trump wins takes the republican nomination and Hillary becomes the democratic candidate after having alienated Bernie voters with the onslaught of accusations of misogyny, deception, political incompetence and so on. Seeing Trump’s decimation of the GOP a figure like Paul Ryan or Michael Bloomberg is thrust into a third ticket run riding on GOP cash.
Then GOP voters that had migrate to HRC in disgust of Trump move to the third candidate. And Hillary who has lost Bernie’s voters during the primaries cannot get them away from their Playstations and their bongs.
Thus, a Trump White House.