I do not believe that Trump has any interest in maintaining a political coalition if he loses in November. He is not a career political activist concerned about building a movement that may survive his retirement. I saw much the same phenomenon with Ross Perot after he lost in 1992. He had put a lot of his own money in converting the United We Stand grassroots operation (predecessor of the Tea Party in many ways) into a political party (Reform Party), but he largely abandoned the party once it became clear he would never be President. The Reform Party limped along for several election cycles before withering on the vine.
Nevertheless, I believe that a third party is possible, whether or not Trump wins in November, because of the sheer number of disaffected Independents and Republicans who have given up on the McConnells and the Ryans of the world. From their perspective, incrementalism is treason; and they will gravitate to a new party that promises to be uncompromising.
Another reason why I see a viable third party forming is that the Reagan coalition has broken apart. Much like the hodgepodge of different factions that once comprised the American Whig Party, the factions separate once the historical reason why they have joined together no longer applies. The Reagan coalition had formed in the context of the Cold War, the end of Jim Crow, the threat of unionism, and the sexual revolution. It was a reaction against the end of Jim Crow, the threat of unionism, and the sexual revolution. With respect to the Cold War, it was both reactive (anti-Soviet expansion) and proactive (“We win, they lose.”).
Today, the Cold War is a relic played out in television series. The last vestige of Jim Crow died when they removed the Confederate flag from the South Carolina statehouse. Unionism is in serious decline, except with respect to the public employees’ union (SEIU). The sexual revolution (now the LGBT revolution) has won, even to the point that Republican delegates cheer last night a self-professed gay speaker who says we must set aside cultural issues for economics.
The historical basis for the Reagan coalition, therefore, is gone. It only makes sense that libertarians will separate from Evangelicals, and noninterventionists from neoconservatives, and that some of these faction congregate as a viable third party.
The Democrats will be the ultimate beneficiary of this split among the anti-Democrats, for I do not see a similar split happening among the Democrats that might level the playing field. The Warren faction may speak loudly about the sins of Wall Street, but they have shown themselves to wield a pretty small stick when it comes to deciding whether to support or to oppose a totally corrupt, Wall Street owned Hillary Clinton. At least, some of the conservatives are principled enough to remain “Never Trump,” though I personally do not agree with them, but where are the “Never Hillary” folks in the Warren faction?