[tomsem]

As I understand it, Adobe gets paid in two ways: by licensing the client side RMSDK to be able to deal with Adobe DRM (including a renderer for PDF and ePub), and by licensing the Adobe Content Server to apply Adobe DRM to ePub and PDF files.

But most vendors ostensibly selling 'Adobe DRM ePub' files (and who have their own storefront-linked devices and apps) bypass this in interesting ways. So for example, Kobo apps for iOS/Android/Mac/PC do not use RMSDK. They use their own ePub rendering engine, and books downloaded directly from Kobo are expanded into the constituant folder/file structure that ePub contains, and these are encrypted with some Kobo-proprietary, device/app-specific key. There's no 'epub file' that you can move to another reading system, even one from Kobo. Because RMSDK is not being used, you can only side-load ePub files without DRM protection, and there's no PDF support, but also no need to 'authorize' the app with Adobe, or for the two-step fulfillment with .acsm files, etc.

Note this means that on the server end of this transaction, Adobe's server is not needed. Only when you request an actual ePub file from Kobo's web site does Kobo's ACS server get used, resulting in some revenue sharing with Adobe. Kobo devices license RMSDK, but only to support side-loading of 3rd party content (from libraries, Sony etc.), and secondarily for the rendering engine. So if you consider that purchases made from Kobo devices/apps directly probably account for 95% of their ebook business, none of these transactions generate direct revenue for Adobe as far as I can tell.

Amazon's system already functions in much the same way, and already supports more than one format (currently, mobi and Topaz). ePub would just be another one. They do license RMSDK for PDF rendering already (since K2); they could use that for ePub rendering, too (might need to modify the existing licensing arrangement to do so), or write their own rendering engine if they didn't like Adobe's. They could also enable side-loading of Adobe DRM epub/PDF so that new Kindle customers could bring an existing ePub collection with them. As added incentive to move to Kindle platform, they could offer inexpensive cloud storage, accessible from Kindle devices/apps, along with syncing and note-archiving.

If they wanted to offer ePub titles to both their own customers and to the world at large, they could use their own DRM for Kindle devices/apps, and Adobe DRM for everyone else (as Kobo and Google do). Only in the latter case would they have to pay Adobe more than they are already (well - except perhaps for RMSDK fees, however that works). It would be particularly nice if Amazon could sell multiformat licenses like O'Reilly ('download whichever format you like'), at least with publishers who agree to that. Kindle devices and apps would still be 'privileged' in such a system, since only they have wireless delivery, free cloud storage, note backup, and syncing services, while everyone else would experience side-loading of some sort, and have to manage their own archiving without syncing.

I would be surprised if Amazon hadn't at least a draft plan for a transition to ePub. The ePub3 specification was just published this week, while we haven't heard anything from Amazon about the evolution of mobi format: no betas, no leaked NDA's, nothing. In the ebook production world, ePub has all of the mind share. But while it really 'makes sense' that Amazon will move to ePub at some point of their choosing, there is no direct evidence that it is imminent, and the indirect evidence is ambiguous.