I am writing a solution because still there is no progress in this issue. :-)
Annotations cannot be saved to ePub file format. Can be saved to the device, but not permanent. One of the most beautiful features of PDF files is that the annotations are saved in PDF. This ensures that the annotations are permanent. I know that some awake users, especially for this reason, have converted their books into PDF. And, over time, more users will discover it.
To IDPF, develop ePub file format can be coming to chore. But Adobe's favorite job is to develop more legible, more functional, portable file format. Adobe may want to develop a PDF version for books. Publishers will want to use this new book file format. Thus, they will have a constantly updated file format. A standard file format! To their favorite job, they can concentrate on the book that to be saved in PDF. Adobe can sell PDF Book editing license to publishers. Mutual benefit is ensured. Adobe already provide DRM for ePub to publishers. I told
Adobe about these issues. Maybe you too would like to send e-mail.
ePub files have one advantage over PDF. User can change font size. This feature is not available for PDF because the PDF consists of many columns and images. But for books, maintaining page layout is not important. Books consist of a single column. PDF Book Version is suitable for single-column. Page layout does not need to be maintained. Font size change feature is available. It is simple from original PDF version. But it has optimum features for e-readers.
Instead of embedded Android e-readers, there are vigilant users who prefer open Android e-readers (like
Onyx vs). Because they are more useful. User can install Android apps on the device.
Kindle's and
Kobo's Android apps can be installed on these devices. Of course Adobe Acrobat Reader's Android app and
Xodo's Android app can also be installed. Over time, it is inevitable for more users to discover open Android e-readers.