In highly technical communications to the FCC, a man named Michael Hartleib makes a strong argument for the possibility of current satellite radios becoming interoperable—or gaining the ability to switch between Sirius and XM as easily as traditional radios do AM and FM. A firmware download could be all that's needed to upgrade the players...that is, if XM and Sirius followed FCC regulations and produced interoperable receivers in the first place. From the way Hartleib tells the story, XM and Sirius are more interested in selling you newer, "dual-mode" tech...
"Dual-mode" allows both signals to be downloaded to a radio at once, as if you were receiving AM and FM concurrently. But that difference—between needing or not needing to switch between music providers—would not be worth the cost of upgrading components to most consumers.
Let me make this one clear to Sirius and XM: if you offer me both services through the stuff I already own, you have a much better chance of up-selling my subscription.
We stole their nice picture, too.