Reflecting on the success of Youtube, it seems that the era of the didactic publisher is over. Everyone is trying to integrate user generated content into their media vehicles now.
Publishing seems to be giving way to the media ecosystem, where users are the primary drivers of content. Indeed, most successful online services have developed a model where third parties are responsible for some, if not all, of the service's content (think eBay, Google, Flickr and even Amazon).
With a huge amount of dross available on video sharing sites, it's difficult to see this ever overtaking professionally produced content, but it does open up a market for semi-professional content generation where enthusiasts (I hate to use the word 'amateurs') can make a partial, if not full living without worrying about running their own media or even dealing with the mediators of TV 1.0 such as commissioning editors and ad agencies.
It may be a long tail, but it's got a hump in its back..