I think the thesis here can incorporate your point about the corporate takeover by saying that more than Trump filled the void left by the absence of effective progressive politicians from the 1960s onward. Corporations filled it as they intended, starting with that 1971 Powell memo. And big corporations captured the DNC, which was easy because Democrats no longer trusted in their progressive principles. Democrats moved to "the center," which meant compromising with the plutocracy pushed by the right.

The alternative to that plutocracy is a social democracy, which the Republicans successfully portrayed as "socialist," in the Cold War. The collapse of the Soviet Union made American capitalism seem like the only way. And Democrats are nowhere near skilled enough mythmakers to distinguish between communism and socialism.