There's no wi-fi technology that can reach a hundred miles with a single transmitter and tower, offering multiple channels as can a single class-c fm HD station. And no technology ont he horizon would allow this. Wi-fi will always be limited in scope. The phone companies have made it clear that they'll sue any attempt at widespread adoption of city-wide wi-fi. And even if they're unsuccessful, it will still be limited, and will be used mostly for "googling". People will use portable computing devices now for basically what they use portable and desktop devices for now. Under 30 percent of Americans listen to internet radio regularly while at their computers, and a huge chunk of that is to the web-streams of terrestrial stations.
Before you whine that it ain't so, 30 percent of Americans listening to internet radio is HUGE. It makes it far bigger than satellite and HD combined (to date). Internet radio IS the "big dog" that's threatening terrestrial...not silly ipods, or other devices that offer an alternate way to listen to MY OWN music library. People listen to the radio for music they don't own, companionship, news, sports, traffic, weather, gardening tips, computer shows (I do anyway), pet shows, oh...and political talk. NONE OF WHICH is available on your ipod (excluding podcasts which reach a FAR narrower range of people than streaming audio. I know, I both webcast and podcast, and have for years).
So you guys have several things wrong. "The sky may fall" on terrestrial radio (I don't think it's possible, but let's say it is for the sake of argument). If it does fall, it won't be because of podcasts, or Ipods, wi-fi, or satellite radio. It'll be plain ole' streaming content, which sounds better and better. Just four or five short years ago, internet radio was intermittent on even a broadband connection, and sounded bad besides. Now sound can be stunningly good, and playback rock solid.
I'd love to be able to add internet radio to my in-car and portable listening. But lawsuits from wireless phone companies will likely keep that from happening without data plans which cost a helluva lot more than satellite, and HD will still offer lots of great-sounding stations, with local content, and NO cost...with an analog fallback for when digital doesn't quite reach...NONE OF WHICH the other technologies can touch.