CDs will stay mainstream for at least 4-6 more years, until some reasonably portable, cheap, copyable media takes its place. I'm just waiting for the damn floppy disks/drives to die. USB keys have got to take off sometime soon--I don't see how people still use a medium that it isn't uncommon to have 5-10% of the disks bad in a new box.
LOL under similar threads: The Demise of Common Sense