A network stream is nothing more than data chunks going from a source point to other receiving points. The same thing can be said about other files. Instead of residing on some server, they can reside on the player itself or on a portable medium. A network stream still uses a data format so that receiving players can decode the data back. Furthermore, as audio files contain a lot of redundancy, they are compressed to save on network bandwidth and hardware costs. Formats must continue to exist: I will not be surprised if instead of one format many will evolve, even for network streams. One reason is copyright security.
All I know is that the new model is to own nothing but to rent everything. Not my favorite model.
