Sound media are the ones you consume while driving, working, cooking, jogging. If the prophets (the trend analysts, the futurologist, the future archaeologists) are right and we are becoming more mobile and nomadic, then sound media will prevail. Mobile screens will always be small, and small visuals are less appealing. (Yeah, I know about those project-on-a-wall or inside-your-glasses things, but, really, how much can you walk around while concentrating on those?)
Prime time in radio is the rush hours. Whatever sound technology the future holds in store, it must work on the commute.
If you're not after the social-communal programming, but want select news or entertainment, then an sound-on-demand service could be perfect.
I worked in a classical music radio channel. We produced 24 hours of radio every day, yet we knew that very few of the (very few) listeners listened more than two hours each day. What if we put all that effort into making three really good hours of programming each day? You could download it to your computer or iPod (and then transmit it to the FM receiver in your car).
This is the insight behind the very important TV anytime initiative. It should be named anything, anywhere, anytime.
Apple offers radio programs in iTunes music store, as well as books. Audible.com offers headlines from a lot of periodicals such as the New York Times or the Wall Street Journal in audio as a subscription service.
I've been toying with the ida of using a shareware RSS-to-speech-to-mp3 generator to burn a CD-RW for my commute every morning. I could listen to my favorite blogs while driving to work!