Lot of folks are assuming a future traditional hardcover release . . . . there has been no official word on that, and personally, I don't think it's going to happen. Mearls did confirm via twitter that once this book moves out of "beta" (or early access, or whateveryouwanttocallit) they will offer a POD option (which, I suppose, could include a hardcover option).
This is obviously another 5th edition product experiment by Wizards (well, even years in almost everything seems to be), and I think we'll get the updated digital release, a POD release, and that's it for this book. And, that's it officially from WotC on Eberron, although we now have the setting open on the DMs Guild. In fact, Baker mentioned on his blog that he's working on a supplement to the book with more character options (no timeline on release) with Rudy Rutenberg, and it's my guess this will be through the DMs Guild, rather than directly through WotC.
If this proves profitable enough to balance out costs and time on WotC's end . . . we're likely to see a similar treatment for other past settings.