The most interesting part of the article was this unanswered question:
“Do Kindle Sales Cannibalize?
The big unresolved question for many houses is whether this spike in Kindle sales is additive or cannibalistic. (Amazon did not update their contention from last year that Kindle customers "buy the same number of physical books going forward as they did before they owned a Kindle. And then incrementally, they buy about 1.6 to 1.7 electronic books.") One executive believes strongly that, while their house's total Amazon sale on big books is rising when you include Kindle and print editions, the Kindle spike is taking market share away from other retailers' print versions (though this point will be hard to confirm until after returns are taken on recent releases). Other houses are just beginning to analyze the extent to which these sales are additive or cannibalistic.”