In short: while it's true that it's less expensive to produce an e-book than a physical book, there's still substantial overhead on the publisher side (read: everything from author royalties to marketing). The combination of the agency model (including the retailer's 30% commission) and the overall lower price point of e-books renders electronic formats only slightly more profitable; in the article, a $26 print book would generate $4.05 for the publisher (note that this is contribution, not net operating profit) whereas a $12.99 e-version of the same title would earn the publisher between $4.56 and $5.54.
Yes, this is a 12.6-36.8% increase in profit, and these numbers would be substantial if sales of e-books were a sizable portion of the market. Since they currently only constitute 3-5% of all book sales, however, their higher profit margin isn't enough to make a real impact on the large trade book publishers entering into agency model deals with Apple. As e-reader technology improves, though, and the prices of the devices themselves come down, it's inevitable that electronic books will begin to assume greater and greater market share. Whether e-books will eventually strike a natural equilibrium with print books (or displace them entirely) remains to be seen.
What do you think, friends & bros? (I like to believe I don't have any actual "foes.") Do you think the current price point for e-books is sustainable? Do you think we may be doomed to a (not so distant) future... without print books?