Consider also that there will remain a role for "publishers" as aggregators of all of that nasty production beyond the actual writing.
As a writer, I may not care to post my potential idea to a service brokerage in order to find competent editors, illustrators, designers, print-on-demand houses, distributors, online vendors, and so forth.
I might just want to punt and sign on with O'Reilly because "I know their work; it's good."
Now, granted, big changes come with all of this ability to make ad-hoc interconnections without the traditional trusswork. What it means to be a "publisher" changes in mechanics, but I don't think it appreciably changes in spirit.
To expand on what I said in another post, the role of the publisher is to connect creators (with other creators and then connect those creators) with customers.
The biggest changes are to the scales at which activities become practical to undertake "solo". I can see a day when William E. Gates' (not the Microsoft one) self-published magazine "Midnight Engineering" isn't such a novelty.
 By "self-published" I mean he ran the web press solo. The web press that he moved across the country with his dad, a forklift, and a flatbed tractor-trailer. That's the sort of nuttiness I admire :)