Nobody works on them because they're impractical.
DSL prices are too high for the average consumer, there is no way they could make money from it.
Anyway, services like XM and Sirius don't have downtime like a lot of internet radio stations. If a server crashes, bye bye music. The only way a satellite radio company has downtime is if their satellite dies, which is more unlikely than a server crash.
I'd say satellite radio will be around for more than 5 years, and even if it's not, why wait? When you want something good and are willing to pay for it, you want it now, not 5 years from now.