I work in ebook production for an academic publisher, and I think at least part of the reason sales have flattened is technological. The current crop of ebook readers are optimized for mass-market books, and have little or no support for complex text or layouts. My life would certainly be easier if I could rely on the Kindle to properly display math or tables, but I can&#x27;t. Apple iBooks is a little better in this regard, also the newer Kobos, but not yet a big market for us. The money, for them, is in disposable genre books, so they have little incentive to do much software development (hell, some days I&#x27;d settle for just consistent behavior across product lines...)