[QasimK]

The same would apply to any digital content (zero-copy cost) which can be substituted. For example, why watch film A when film B is available more cheaply. Of course, it's difficult to have substitutions for entertainment (for various reasons)... right now.

However, I do think the long-term trend here is downwards as well and I'd use music as an example. With streaming services, the cost of music is much lower compared to purchasing music. The streaming service acts as an aggregator for different content and has an incentive to pick the cheaper content (with the opposing force of consumers wanting particular things). But really, if the quality is high and the music chosen to be played is automatic (via recommendations) the underlying artist is less significant (in general - I know people can be fans).