Pages and page numbers are just a solution to a problem (essentially how to you manage a very long scroll). Likewise, things like footnotes, endnotes, citation numbers, etc. are a solution to the problem of how to include "non-linear" information that can generally be ignored in the "narrative" of the text. Now we have better technology, so the solutions will change.
That said, it will take time for people to move away from the page number concept. I think technical and scientific will move away far faster, and from what DixieGal has said, they already are. In the more conventional area, people feel more comfortable with the idea of a page number (23 pages to go till the end of the chapter, etc.), so that will remain.
As to finding passages, etc., that should be much easier with the idea of bookmarks, etc.
(Incidentally, page number references are only useful if you have the exact right edition of the book. I remember some chaos at school when a new cheaper edition of a set text was introduced, resulting in two sets of page numbers....)
Ecoutez Zelda, unless you want to live in interesting times