Music is easy these days. Pick up your smartphone, whatever its make and model. Open up Pandora. Punch in a favorite song or artist, and rock for hours.

This is the future of radio: personalized, always-on mixtapes of infinite variety, all delivered via wireless data connections. You'll notice that I'm not dragging satellites into this. I think Sirius XM Radio (Nasdaq: SIRI) will start to fade away as soon as the general public gets wind of this hyperflexible alternative -- especially now that Pandora, like satellite radio, is finding its way into new cars.

In response, some Sirius fan will invariably point out that most new cars come with Sirius or XM radios preinstalled these days, either standard or as an option. A few free trial months are the gateway drug, and then you're supposedly hooked on a service you'll never want to live without again.

Well, baloney. Sirius services are cheap, but Pandora is free if you can live with an occasional ad spot or two. That's a tough price point to match, especially if you're on an eternal search for solid profits. And Pandora is making its way into new cars, too.

The streaming music service has announced deals with luxury veteran BMW (OTC BB: BAMXF) and Toyota (NYSE: TM). The service is integrated into Toyota's Entune telematics system and BMW's ConnectedDrive, giving you control over Pandora from a center-console dashboard screen, and plugging right into the cars' speaker systems. It's still an early draft of streaming-enabled car entertainment, and will depend on a data feed from your smartphone. Still, it's more sophisticated than jerry-rigging your phone into the car stereo via FM transmitters, AUX plugs, or (shudder) old-style tape-deck kludges.

In due time, the phone will fall away from this ecosystem, to be replaced by the car's own data connection. I'd expect Toyota and Ford (NYSE: F) to sign data deals with network providers for free inclusion with a new car -- like the way Amazon.com (Nasdaq: AMZN) powers its Kindle Whispernet with AT&T (NYSE: T) 3G networks without charging any monthly fees.

That's where we're going soon enough, which is why you can't convince me to buy Sirius stock. Satellite radio is a stopgap service that will soon become obsolete -- if not by Pandora, then by some better version of the same idea.

Add Sirius to your Foolish watchlist to follow its inevitable death spiral in gory detail.

Fool contributor Anders Bylund holds no position in any of the companies discussed here. Amazon.com, BMW, and Ford Motor are Motley Fool Stock Advisor choices. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. You can check out Anders' holdings and a concise bio if you like, and The Motley Fool is investors writing for investors.