HD Radio's proposed "possibilities" seem out of touch to me because of the sheer proliferation of communication platforms in general. When FM was introduced, it was basically just another way to do one-way radio. It took decades to take over, but it did it in a world of three mass media platforms (print, TV, AM radio). FM had time to make its mark, and the public didn't have to learn anything new (though they did have to buy new receivers). HD Radio's propositions seem bound in this FM radio world view -- the idea that it will reach near-ubiquity because FM radio did. But HD Radio is entering a market that has not three major mass media platforms, but perhaps 10 or more (depending on how you count). Not to mention that one of the mass platforms out there today -- the Internet -- is not a medium but a transport system that can carry ANY medium. Why should I, as a consumer, adapt my listening habits and spend more money on a media format that's basically an update of the 20th century's greatest hit when I could simply shift over to a multimedia device that can get me audio, video, text and still photos and has a wider reach than any one radio station?
All this said, I do think an HD Radio rollout is called for, if for no other reason than multicasting. I'm just deeply concerned that the "neat" stuff HD Radio "could" do is oversold and cannot possibly deliver -- not technologically, but in terms of market acceptance.