A "publisher" in the digital world will be a very different beast and it will be hard to call it such. Most of it will likely be automated. Their core-competency might not even be book-publishing.
Are Amazon and Netflix "studios"? No, but they do produce high-quality video content. Is Louis CK a "studio"? No, but he's producing a TV series.
Publishers' functions (content editing, packaging, distribution, marketing and merchandising) are being split and reorganized in different ways. Verticals built on the new production chain will look very different from current publishers.