Amazon will also continue adding .apnx files to books, focusing most heavily on big sellers & non-fiction books that are more likely to require such reference.
I think the method you are using, user_none, is just dandy for the rest, and most important, it seems to be the only way toward a standard for all ebooks.
IOW,
"only looks at visible text.
Each page is comprised of
n lines and each line can have up to
n characters.
A paragraph always starts a new line.
<div class="mbp_pagebreak" /> = new page
...could become the standardized ebook page* so people could settle in with a feel for weight, and all e-versions would match
(closely enough) across all formats, regardless of fonts, margins, etc...
(*Call them pages, locations, blocks, whatever everyone wants to call these
chunks that give humans logical points of reference and progress. I just use page since it's simplest as a common metaphor.)