Ebook has certainly gained much grounds over printed books. There is no doubt that ebooks will replace most of printed books in time to come. With modern technology, I see no reason why ebooks cannot be further enhanced, other than simply imitating conventional books in electronic form.
For starters, how about including music and sound effects at various points in the book? I remember that as a child when I was reading children's books, I loved the illustrations. They helped to bring the story alive. If the ebook author could include a clickable music icon or a sound effect icon here or there, one could bring the sound to live as he continues to read.
Even video clips would add to the reading thrill. Say you are reading a book after a movie has been made or released. A video clip at selective points in the book will further bring the story to live. Or, if you are reading a biography, a video recording of the subject will bring the person to life. You will be able to see the person and hear his voice.
I would also like to see at the end of the book, a list or recommended readings by the same author, or of the same genre. This is already available in the back cover of many books. However, it can be enhanced now that it is far easier to include a far richer content in an ebook without being intrusive.
The technology is all available now. It is just a matter of taking advantage of it to re-invent the book.