For decades the mainstream factions of the two parties have just counted on everybody else just falling in line. The old school, rich, fat cat Reagan/Bush conservatives could always count on the blue-collar conservatives, the Christian fundamentalists, and nationalist/white supremacists to all just fall in line under the GOP banner. So, they looked the other way on the bullshit, so long as they got the votes.

Same with the Dems, with minorities, environmentalists, social justice factions...etc.

The Venn diagrams are pushing further and further apart. Trumpism has pulled back the curtain on the GOP, and shown that what folks like Mitch McConnell and Lindsey Graham might have once just considered useful idiots, are far from "conservative." While not as volatile, the progressive wing is definitely fracturing the Democrats.

We may be seeing the death of the two party system.