Given all the complexities one must deal with in producing a truly compatible ebook file, with Adobe InDesign as a good example of an app that has been perfecting this route for years now, it sounds like a noble but extremely challenging goal. Epubs aren’t of much interest unless they can be used with at least the top 2-3 readers, which probably means at least Mobi and Kindle, and those formats are still in flux. Most ebook formats are really HTML-based websites, hidden in a single archive file, so they can be modified after they are generated, and unfortunately I’ve had to do some hand-work on output destined for Kindle every time I’ve produced an ebook. There are some very powerful tools available for managing this process, and it doesn’t seem practical to build these capabilities into a tool (AS) designed mainly for writing (rather than for publishing). There are also online services for quickly generating reasonably good ebook output, but all the authors I’ve worked with ended up hiring a consultant to produce a high-quality, fully-compliant, multi-platform ebook, even when the original print version was very well designed and managed inside InDesign. So while ebook output sounds like a great capability, it doesn’t seem to me it would be a practical direction for a streamlined app like AS. A nice clean PDF, with a little bit of layout control, would be a useful compromise.
Just my tuppence.