There's probably a lot involved in this but it seems like you've done most of the world already in converting (X)HTML to a paged media (and doing an excellent job at it too I might add).

Although the format is different, a lot of the same concepts apply (headers, footers, cross-references, footnotes, indexes aka document maps, etc).

Anything like this planned?

We tried this a few years ago, and it was a world of pain and misery I'm afraid. Basically, the transformation is too lossy, and it is too easy to create files that make Word crash. There are companies that devote entire products to interoperability with Word, such as upCast.

In a similar vein, are there any plans for an RTF output option?

To allow users to download a very nice version of HTML into an editable format (e.g. tables with content within them that they wish to update for personal use)

No, this is what we tried, and it wasn't fun. Take a look at upCast, mentioned above.