That's BS that they could get 30-million subs. Radio is free everywhere. Why pay for radio? MP3 is a viable option for those who don't care for what's on radio.
It's hard to get in a building, in mountains, and other areas. Why bother?
It's a niche, and that's all it ever will be, IMO. Look at Tivo and see all the market potential. People love it, but not enough to pay for it.