SXM's business model has no future, especially at the rates they charge and the infuriating "royalty fee" they tack on.
And yet, as the story in the OP says, they're making money, and it is growing. So while YOU don't like it, a few million others do. That's what the media world is about these days. So as long as a few million pay their bills, they will have a future. But no matter what they do, they will not "dominate" the dashboard.
What surprises me is that the cable company that owns them hasn't figured out a way to bundle Sirius with his other channels. Then again, cable is another business that is being chipped by other media.