I think that with the rise of wifi in mp3 players that someone/me will make a good sturdy device with a wheel or something to be able to easily navigate through MILLIONS of songs because by this time the world will be almost completly networked using cell towers, satellites, and wifi and etc that you use your device to connect to a service that has every song on it and you just stream it and if you like it you can download it to your device for listening in space. You will be able to put your stuff on the service for free under the CC license (creative commons) and if you want to watch videos on your device you can because it also has memory! The device will also have a social networking feature similar to Myspace or Last.Fm. Any idea's, Improvments!? Insults!?

I guess it is a nice concept. But I think it won't be called mp3 player anymore. Perhaps, put your concept with PDA will be much more worth it.