You use Sirius as an example, but that's missing the point. It will be the combined impact of all satellite formats, plus the effects of streaming internet-to-go, plus the effects of easier to use personal music library play-back systems, plus whatever additional new technologies that come along that will collectively, as a group, gang up on and beat terrestrial radio into a feeble, bloody pulp. It won't be dead, but it will be a feeble shadow of its former self.
Or, they are like me, who used to look forward to listening to the radio and who now regrets the loss of one of his favorite entertainment media because it has turned from something "lively" into something that's more like a wax replica of something alive. Calling radio "dead" is usually hyperbole. The more apt comparison is comparing a bowl of real fruit or flowers into a bowl of plastic replicas of fruit or flowers. Radio used to be "live", now it's "fake".
You do know that most of the satellite radio music programming is hosted with voice tracks? To that point.. The most recent statistics I've seen (I believe it was from BMI) show combined satellite radio (which started in the 90's) peaked at less than 3% of total 'radio' listening and is holding right around <1.3%. Ironically it appears that Pandora, Slacker, etc. have actually cannibalized more from satellite radio listening than terrestrial radio. David may have more current statistics, but suffice it to say that neither satellite nor streaming combined, has taken much of a bite out of traditional radio listening, even considering satellite radio has been going for over 15 years.