This is an intriguing idea. Contributor [1] by Google is an implementation of this concept for content websites. Netflix is an implementation of this for television syndication. Amazon Prime is an implementation of this within its own diverse consumer-facing ecosystem. The MPEG-LA licensing pool or the HDMI licensing pool and various trade associations are implementations within their respective fields. In their respective circles, these work well. So well, in fact, that everyone wants their own slice to control.
I believe that's where the idea of an overarching meta-subscription breaks down: the incentives don't align. When a BigCorp can (theoretically) establish a horizontal and a vertical, and offer a smattering of products for every need while at the same time producing a family-tree of highly integrated offerings (see: Google, Apple, Microsoft, Amazon, AT&T+DirectTV, Comcast+NBCUniversal, Verizon+AOL+Yahoo), the remaining players are fighting over pennies of the pie. It's not worth it for them, and it's not worth it for the big players, because they already have the presence, the lock-in, or the content worth paying for.