In a trail of observations that began with Trump's campaign in 2015 and peaked during the last year of his life, the late Rush Limbaugh, as he was in and out of the studio battling cancer, was on a path to the previously unthinkable. He was ready to let go of the ideology he'd spent three decades promoting — Reaganite conservatism — and replace it with right-wing populism. Specifically, the right-wing populism of the just-defeated Republican president. Why? Limbaugh, the self-proclaimed "mayor of Realville," was constantly trying to see around corners. What he saw was a political movement that offered...