Subscription = more diversity
Ivan's post brings up the real advantages of subscription service (Sirius, XM or even cable TV's Music Choice). Revenue and costs have little fluctuation in subscription services (if there is any fluctuation, it's from revenue growth). With that kind of profitablity, it is easy to provide a broader range of service. Also, because the listener base is not limited by geography or transmission range, the demographic base for subscription services is greater.
If you want the best specialty programming, it isn't to be found on FM's mass-appeal formats. Get a subscription service ... spring for the few extra bucks to improve your listening pleasure. Or program your own music on CD's, MP3's, tapes or any other media you prefer.
Years ago, in the 60's and 70's, everyone was sure that "Pay-TV" would kill the movie business, Broadway and television. Maybe it will someday if film, TV and Broadway don't continue to evolve. FM Radio, on the other hand, still has not found a legitimate way to battle all the personal listening choices make music easily accessible beyond the radio. And without the blasted commercials.