This is an interesting article on the future (or lack thereof) of book covers.
Personally, I don’t see there being an end to book “covers.” Pictures capture the eye. One thing bloggers and website builders are told to do is add a lot of pictures to their content because “a picture is worth a thousand words.” No one is going to stop putting pictures with books; it actually makes them harder to sell because there’s nothing to catch the eye.
But there will probably be some sort of revolution in book pictures. Most likely they will become interactive or animated. Maybe there will even be a picture per chapter and you can use the pictures to navigate the table of contents like with a DVD. (Obviously that’s something more for the traditionally-published market; I’d pull my hair out if I had to design a picture for every single chapter of my 32-chapter book.)