Yes. He has successfully been dropped in New York and other major markets!
Yes he wouldn't be as successful in some liberal markets and he also doesn't work as well either on the radio or TV with those who just want sound bites rather than in depth analysis.
I don't watch or listen to a lot of Beck because he does go into such detail and brings in so many technical components that you don't get it if you can't spend the time to pay close attention. So WOR did drop him, a station in Connecticutt dropped him, and no doubt some others even as others were glad to take him on when the air space opened up. You will generally only have one station in a market area carrying a program like that.
Glenn continues to be carried by more than 400 stations across the country which puts him on a par with Limbaugh so far as stations go. He doesn't pull the ratings that Limbaugh does, but he does well enough.