The changing face on music.

Listening to music has changed over the years-from vinyl records that got scratched and you ended up having to put a coin on the stylus; to cassettes that stretched with time or needed respooling with a pencil; to CDS which weren't as indestructable as claimed and to Mp3s where you don't need to physically own anything and you can store an entire music collection on an ipod the size of a matchbox. What does the future hold?