In a nutshell, a good car will last 10+ years but a smartphone / gps / high-end stereo interface starts getting long in the tooth after 2. Article at ITworld accompanied by assorted smartassery at Slashdot.
The solution in my latest car? Basic AM/FM/CD stereo with an aux port, a la "earbud jack input." An aux port is compatible with everything from the latest iPod down to an old cassette Walkman (yes, I have one, even use it occasionally), and it's a damn good bet that the aux port will continue to be compatible with just about everything for the next ten years.
Still need to get a smartphone though. Maybe early next year.
BTW, kudos to Ford for putting out a damn fine radio in their '12 cars. Even with that cute little 18" rubber ducky antenna, it pulls in FM like a champ and AM almost as well as my home shortwave set. I'm betting there's a DSP chip in there somewhere, at least on the AM end.