I was expressly excluding it since (a) it hasn't shipped yet and (b) I
couldn't speak for it, so thanks for confirming that hope would be futile.
Also, when I said "do not offer any way to do what you need," I should have
qualified that as meaning that Word does not offer any built-in, automatic
way to do it. It could be done with a text box anchored to the header
containing line numbers, but (a) they won't be accurate unless the line
spacing is entirely uniform and unbroken, and (b) they'll restart on every
page. For those reasons, I don't consider this a viable option.