While using my iPad to read will never replace my tactical experience with a book...
Nitpick - I asusme you meant 'tactile'?
And I'm in much the same position - while I'm happy to read short articles online, and will read entire books online if I
must, I very much prefer physical books.
Thus, while I will argue that every 5e product that can be released in electronic form
should be released in electronic form, that needs to be
in addition to the physical version. If the game goes electronic-only, or even if it requires an electronic component (or even 'requires' it as much as 4e 'requires' the Character Builder) then that's a deal-breaker for me.
(And, ideally, they'd adopt something of the Paizo model - buy the physical copy and you get the electronic version at a much-reduced price. eBooks are great for reference, but I won't use them for reading, and I won't pay twice for the privilidge of having both!)
All of that may make me completely unreasonable, and it's also very likely that I'm not WotC's target audience... but it is where I stand currently, reasonable or not.
Will the virtual bookcase use larger images? Will animated images come into play? (Egad, I hope not! Can you imagine a browser page full of animated covers?)
Indeed, I would expect animated images to come into play the moment some marketing bod decides it's a good idea. And as soon as anyone starts doing them,
everyone will start doing them. And it will be just as horrible as you predict... but that won't stop it.
In the world of print, the cover plays a major part in the buying process...
That used to be the case, but really isn't (for me) any more. There are either specific authors I follow (Pratchett, Cornwell...), or there's a book that I've been waiting on for some time (most D&D books). Or, failing that, I'll have cast around for recommendations, either from Amazon, from friends, or otherwise. Actually, my process for buying physical books almost exactly matches that described for buying digital books.
Simply put, I can't remember the last time either the cover or sales text of a book had
any bearing on my buying decision.
As I'm looking at the world of digital books, I'm seeing that the purpose of the cover is beginning to operate in a very different manner.
In the physical realm, the purpose of the cover was to protect the contents from the elements (hence the name). The pretty picture and sales text came after. In the digital realm, the 'cover' is obsolete - there are no pages to protect.
As a result of this, the cover should be treated as pure advertising - by all means, attach it to the digital file if you like, but there's little reason it couldn't be provided separately, or indeed not at all. After all, anyone who wants to look at pretty pictures can do so easily enough online - indeed, what was once your cover will now be available anyway, as a banner ad, in the previews on your website, or as a place-holder on the Amazon page.
Should the cover design have different versions for brick-and-mortar stores and for digital presentation?
No, but only because it's easier not to. If you've got a physical book of a particular size and shape, it will need a cover of an appropriate shape. Since you've then got the image in that shape
anyway, there's no good reason to do anything different for the digital version (though scaling it up and down is trivial, of course).
However, if you're going digital-only, there's absolutely no reason to be bound to the needs of the physical medium. So, by all means have a hexagonal cover on a rectangular novel, or no cover at all, or even a set of covers that randomly switch each time the book is opened.
Should the use of art change depending upon the sales channel?
No idea.
Does a change of cover treatment cause confusion with the buyers?
Not in general. But if WotC are going to continue with their policy of reusing book titles from old editions, they should probably stick with a single cover for this edition's version.
Do they notice or care about the differences in a cover from one version of the book to the next?
Sometimes. I recently bought a set of the James Bond novels, and did so in a piecemeal fashion. I happened to get the first few in a particular cover style, and so proceeded to make sure I got all the rest to match. Likewise, when buying the Harry Potter novels, I selected the "children's version" of the covers in all cases (though I ended up getting the last volume, only, in hardcover).
Does the role of the cover have a different purpose to the consumer in the different mediums, or it simply a business issue?
As I said above, in a physical version, the key purpose of the cover is to protect the contents from the elements. In a digital version, it's just a pretty picture.
Should a digital cover try to look like a book cover on the virtual bookshelf, or is that an antiquated concept?
My guess is that now that books have gone digital, they'll start blending into every other medium. So, we'll start seeing 'books' that have built-in soundtracks for each chapter, or 'books' where you can opt to have the character dialogue read to you by a cast of actors, or 'books' where entire segments are actually videos.
So, for the moment, digital books look and act like physical books. They probably will for a couple of years, while adoption of digital readers remains relatively low. However, as soon as you see anyone dip their toe in the waters of multimedia books, you should make ready to follow suit, because once they take off, they'll probably do so fast.