David Tebbutt at IWR neatly summarises a hypothesis from Kevin Kelly that in the digital age anything that can be copied and distributed for free becomes worthless and that therefore value resides only in associated non-copyable attributes.
Kevin categorises these attributes as: immediacy, personalisation, interpretation, authenticity, accessibility, embodiment (a non-digital representation, eg a book or performance), patronage (paying a reasonable amount to the originator) and findability.