From the perspective of a tech person, and not a publisher, it sounds like you're book will only be satisfying on tablets and computer. Adding to the reasons mentioned earlier, using InDesign to publish an ePub/Mobi title sounds like a big faux pas since InDesign focusses on page layout while ePub/Mobi pretty much destroys the page layout in order to reflow the text different shapes and sizes of display. Since most eink devices use some form of ePub and Mobi, they wouldn't work well for your book. (Yes, they support PDF too. But there are a lot of complaints about how popular eink devices handle PDFs. While you can design a PDF document that is friendly for small screen eink devices, you would also be limiting its value for table/computer/POD readers.)