I know there's a ton I don't know. As Jon Stewart says, shouldn't I *want* the government and judges to be smarter than me?
However, I should think there'd be more examples brought in of "lexicons" and other guides that are (a) on recent works, and (b) not licenced or approved by the author. Or possibly part (b) is where they go into transformative use. Or some of those other definitions and interpretations I'm not expert in!
As to the outcome, I would share your hope that a win for RDR not be a death knell for fanfiction. OTOH, I'd hope a win for JKR not be a death knell for fan creativity, ushering in an age of authors controlling everything up to and including who gets to have a fan site and how people are supposed to read the books (which JKR's done; the more I read the more I see how startlingly sweeping her claims are, even in the context of a voracious global media industry).
But really, I think there's even greater reason not to follow the "slippery slope" of assuming that "sky could fall in" = "sky *will* fall in." There seem to be increasingly frequent End Of Fandom As We Know It panics sweeping LJ, etc. One of these days, the sky may indeed cave in on fandom! But meanwhile, a lot of arguments I've read in this latest kerfuffle seem to make the mistake of overusing this fallacy to abuse the opponent: "If you don't support JKR liek totes, you hate fandom! And UR a muggle! And ugly @(*&$#^! too!"
I don't see that this case has any bearing on fan-fiction. But as always, I am eager to see further information.
ETA: I just read through Janet Sorenson's very interesting history of lexicons and such in English literature. Fascinating! 18 pages, at RDR's site. With regard to one of your specific points up above, I don't see her listing any of the myriad guides to, say, Tolkien, made during copyright, being made in direct opposition to the author's wishes. Although (a) that issue isn't the main topic of her deposition, and (b) I seem to recall a *lot* of biographies of people that were vehemently objected to by the living subjects. And if you can publish, for profit, a Kitty-Kelly-like tell-all scandal bio dwelling on intensely intimate details, why not a book about a fiction book? I know, I know, different areas of (our crazy quilt) code of laws. But principle-wise... seems ridiculous to grant a degree of entitlement to "privacy" over a widely sold make-believe story's characters than over real live people. Maybe JKR's thinking of HP as her "children" is a metaphor leading some to think that all the same laws apply.