Downloadable music will also die. Spotify, or equivalent streaming services, have the clear killer feature downloadable music is missing - access to all music on any machine with an internet connection. Carrying around your data will seem antiquated really soon.
Edit: For the US readers I'd like to clarify that I don't count any other existing services as equal to Spotify, but there will surely be copycats soon. It is the iphone of streaming music applications if you like analogies.
I'm one of the 9 million new yorkers who take the subway to work every morning and work in midtown. If I had to rely on a net connection for music, photos, etc I would be without a great deal of the day. (During transit, at 5pm, in some office buildings.)
I also don't like the idea of renting, music, property or otherwise.
Memory will always be cheaper than bandwidth and far more pervasive. It makes no sense to download something, then 10 minutes download it again. We already have pervasive non-downloadable streams - it's called radio. It's still popular, but has never completely displaced having your own collection.
One of the killer uses of digital music is the ability to have a miles-long playlist for long road/plane trips. Downloadable streams cannot possibly service this market cheaper than a solid-state memory device. Wherever you have a market segment that needs two devices, the one that combines both always wins. So the future is an iPod that can stream if necessary - which we already have in the iPhone.
Edit: For the US readers I'd like to clarify that I don't count any other existing services as equal to Spotify, but there will surely be copycats soon. It is the iphone of streaming music applications if you like analogies.