It's probably coming to an end. I don't just mean him, but that particular brand of conservatism. It's pretty weird to remember, but when I was in college Limbaugh was actually kinda cool with the kids, with the dudebros of the day who fancied themselves "intellectuals" buying his book.
But conservatism isn't dead, and neither is conservatism for the young or a young audience receptive to conservatism. Culture's a bit more fractured now, but presumably there's the new version of the Limbaughs out there who I'm not even aware of.