What I want to see is some way to differentiate index entries in an ebook. In print, I know that “125-138” indicates more in-depth treatment than say “125” and indeed, “125-126” indicates something different than “3-4”, even though it’s the same number of pages, just because we know that “3-4” is probably in an introduction.
And how are we going to label index entries at all? Of course, page numbers won’t do it. So what’s the alternative? Could size or color indicate depth? A bar that grows or shrinks according to depth?