Well, I was right. XM satellite radio is 64Kbps [wikipedia], and Sirius uses about 96Kbps. Excerpt from a Sirius receiver product page [electronicexpress]:
That's just horrible. I can barely stand to listen to my old 128Kbps mp3's anymore, I rip all my music at 256Kbps. When I tune in on Shoutcast, I only listen to channels with 128Kbps or higher. There's no way I'm going to listen to satellite music at anything lower than 128Kbps. Especially if I have to pay for it every month!Beyond the reception issue,
the only other major drawback is sound quality, which some may find
subpar. Sirius describes its sound as "digital quality," a euphemism
for "digital audio with a bitrate so low that we don't want to scare
people by revealing what it is." Whatever it is, its character is very
close to what you'd hear from 96 kbps MP3--clear and listenable, but
lacking depth, fullness, high-frequency extension, and dynamic range...
So much for satellite radio.
What's more likely to happen in the next year or two is that your cell phone becomes a streaming audio system at a higher bitrate. It's wireless, and more portable than any receiver bolted into your car. As the bitrate increases for data communications on cell phones, it can be used for anything, not just music.
As far as I can see, satellite radio is dead.