It is a guess based on the size of the storage that has been purchased, the fact that video consumes far more data than audio, and the introduction of a simple audio locker or cloud-based version of iTunes is unlikely to require this much storage and capability out of the gate.

FORBES: Apple To Launch Video-Focused Cloud Service, Jefferies Contends

The vastly increased access to a major art form that resulted from the introduction of audio recordings of music in the 20th century.

ECONOMIST: Letters

With the introduction of 3D audio technology, the aural aspects of travel are set to be revolutionised, in the same way 3D movies like Avatar and game consoles like the Nintendo 3DS are revolutionising visual entertainment.

BBC: 3D audio may revolutionise travel