Here is the counter argument. The Trump base is now the Republican Party. All of America’s non better angels have flowed into the GOP over the last thirty years, being dog whistled there by the likes of Newt Gingrich, Fox New and conservative talk radio. They are not all bad people, but perhaps being rather less sophisticated than average, they are unware that they are on the side of bad people like shinheads and the klan. And these latter types love Trump because he is just like them. So there’s not likely going to be any massive melting away of Trump supporters for any reason. On the other hand, Democrats could very easily fall allover each other in a disastrous way trying to be the one to defeat him.
Let me amend this piece and say that the Republican Party has been subsumed by Fox News. This is why Trump watches it religiously — to get his marching orders. It is why most of the old GOP establishment can’t bring themselves to go against Trump. Trump’s base is the audience Fox nurtured, and thus it is the base that has overrun traditional Republican conservatives. Indeed, there is no traditional Republican Party anymore, but you might see some of the old guard hanging out at MSNBC these days.