All of which means that whichever conservative pundit inherits Mr. Limbaugh’s golden microphone is unlikely to command quite the same sway. Jimmy Fallon may host “The Tonight Show,” but he’ll never be Johnny Carson.

“There’s so many different platforms to interact with conservative voices, and there are so many more voices,” said Ryan Williams, a Republican strategist and longtime press aide to Mitt Romney. “If you’re pro-Trump, you’ve got Breitbart and Newsmax. If you’re more of a moderate Republican, you’ve got The Bulwark and Charlie Sykes. I follow 25-, 26-year-old conservatives on Instagram who are sharing two-minute videos that young people connect with personally.”

He added, “I don’t think you’ll see it ever again where one person is the king of this realm.”

iHeartMedia, the Texas-based radio conglomerate run by a chief executive in New York, Bob Pittman, controls the fate of “The Rush Limbaugh Show,” which appears on roughly 600 stations nationwide. For now, the syndicator is re-airing the “Best of Rush,” introduced by a rotating group of guest hosts.