Instead of the "directly-streamed linear programming" model, you
could do radio audio broadcast the same way you do GPS: just have the local radio towers spraying some selection of podcasts on a loop (with high enough frequency+bandwidth+compression that the effective audio rate is faster-than-real-time, unlike satellite radio), and then have "radios" in cars (or wherever) which catch the files and cache them.
You can build whatever you like on top of that—a hybrid device that will siphon up local OTA content along with arbitrary podcasts when it can find 4G, and then intelligently arrange the combination into linear programming, for example. (Really, though, you're just creating a weird sort of secondary internet that only allows retrieval of files relevant to the local area. In fact, you could make the "radio" into a 4G picocell that actually re-serves said limited internet to your phone, where the OTA content then shows up in your regular podcast app.)
Effectively, this would be the over-the-air equivalent of how pay-per-view (not video-on-demand, the older one) worked, but with the client device then acting as a set-top box to turn the received broadcasts into something equivalent to video-on-demand.
This would also be equivalent to how the http://en.wikipedia.org/wiki/Satellaview received game programs.