That article seems like a winning buzzword-bingo game by someone selling blockchains.Anyone who wants to sell online already can and there are plenty of people who do with either no middlemen or by picking a third party who shares some philosophical goals. Similarly, unless you're trying to sell completely illegal content it's trivial to buy or sell content which the major players choose not to carry — e.g. iTunes and Netflix not offering porn hasn't seemed to prevent anyone from watching it.
The actual problems here are discovery and piracy. The former increases the benefits (real and perceived) of middlemen with promotional channels, speaking to both to the creators wanting their work to be found and anyone finding it. The latter is similarly important: most artists don't make money so every lost sale counts and for every artist who believes content should be unencumbered there seem to be more who demand DRM, especially the mainstream ones with the most customers.
Not addressing both of those is fatal: if customers can't find what they want easily, the service is unlikely to make it out of the indie market. The key thing to remember is that outside of the diehard anti-DRM community, nobody sees this as a problem – most people find what they want on a major service, pay an acceptable amount, and leave satisfied.
Blockchains don't solve those problems and add new ones, like performance and irrecoverably failing open if there's a bug, which are likely showstoppers.