Anyway, my opinion on the "next format" is an odd one. I feel that since USB Flash Drives are dirt cheap (18 bucks for a 2 gig drive) they could conceivably be used to store read only data.
You've got a compact item that can replace any aspect of the CDs. It's portable, you can have a portable player, and while the data rate is not the best, it will improve over time.
Then you can also buy a bunch of "blanks", download music and boom you can have "physical copies" of downloaded material.