The dominant theme in political discourse changes frequently. As politicians figure out that most of the public is tired of one theme, they pick up another one, and it dominates for a while. Rinse, lather, repeat.
A few years ago the dominant political theme was inequality. Now it’s racism (or, more broadly,
discrimination “hate”). Dominant themes of yore include anti-communism vs. anti-anti-communism, relations with the USSR, civil rights, and various wars (especially Vietnam and Iraq II). The economy becomes a dominant theme when it’s down, giving politicians an excuse to promote economically destructive spending and redistribution schemes.
What’s next? I don’t know, but there will be a dominant theme, possibly before the end of Trump’s first term. One possibility (though it may be too arcane) is the power of the information-technology giants, which is being attacked from left and right. Something “sexier” is sure to come along.
(See also “The Age of Memes“.)