I think his economics are off when he says that "The network effect is being repriced to zero." What's happening is that a strong competitor is emerging, and the network effects of eBay aren't that strong that people won't migrate for a significantly better price on a network that sees a reasonable amount of business.

He has one interesting point, though: will competition drive the seller's costs down so far that eBay becomes a glorified classifieds listing? If so, then it's also competing with free listings other places.