Sure it could be done in a software upgrade... I assume they dedicate some screen realestate to such things as signal strength already, so there is likely no GUI issue.
The one area I would really like original page numbers (not the repagination that occurs on the reader itself), is technical manuals, where you would likely interface with a hard copy (or someone with a hardcopy) at some point.
So if it took me three reader pages to read one "original" page, then so be it. And the page # should always reflect the "original".
THAT would be difficult to determine with just a software update.