I listen to the radio mostly in the car, although sometimes I will listen to online stations. I like rock, particularly classic rock, so I listen to that almost exclusively. The funny thing is that when I listen to the radio online, I don't listen to anything local--I like The Drive, out of Chicago.
With all the Wifi hype going on around, we may indeed one day be all listening to internet music, even while driving. Ford appears to be the first one to do it. Their new models now incorporate mobile wifi. Ain't that absolutely cool?
It may be awhile before we see the Radio go away. Now that purchased radio formats exist, that area will continue to grow and change. Also talk radio shows have gained a lot of popularity within the past 10 years.