When I heard the news about a possible third film, my first thought was: the Appendices and other sections of The Lord of the Ring provide nice snippets, but I couldn't imagine many things with a dramatic structure, particularly things that people who weren't already fans of the book would care about.
The one exception is probably the hunt for Gollum and for knowledge of the Ring. I can see a conversation with Saruman piquing Gandalf's interest. Maybe a trip to Rivendell to interrogate Bilbo one more time, along with some other Rivendell scenes. Maybe we meet Aragorn there on one of his trips to see Arwen (because apparently Tolkien movies must have romance, even when they don't). Aragorn and Gandalf realize that Gollum is the key and hunt for him for a while in frustration. Gandalf breaks off and goes to Minas Tirith where we get intellectual maneuverings between him and evil!movie!Denethor (oh, please, couldn't we make him smart? Even that would be an improvement...), and Denethor gives Gandalf access to the archives almost as a dare to actually find something about the founder of Gondor that Denethor doesn't know. Assisted ably by Faramir - in direct opposition to dad, a place for wimpy!movie!Faramir to show his character - Gandalf finds enough to form a theory. Meanwhile, Aragorn through great feats of will and against all odds, finally captures Gollum and meets up with Aragorn somehow. Contrary to what the book is, they don't beat the information out of him but somehow give him a chance to give it up willingly. Gandalf rushes off to the Shire, while Aragorn takes Gollum to Mirkwood. It could end on a nicely redemptive note, but not in an uncomplicated way - leave the question of whether Gollum is really reformed and whether he'll stay that way.
Even that, though, seems strangely anticlimactic. I mean, how exciting is intellectual discovery if you're not an academic? Even politics seems beyond what Jackson can manage well. And the whole thing ends without the point of all the sacrifice and effort being made clear; it really just is a set-up for LOTR.
There are other things I'd like to see explored, like Balin's colony in Moria or the family struggle to get Frodo to live at Bag End, or how the various elven kingdoms related to each other. But I'm honestly not sure how you'd give that any kind of a dramatic structure, and that's what I was really asking about. We all have our favorite characters and moments, but there simply doesn't seem to be a *narrative* worth telling here.
Anyway, that's the kind of thing I was looking for. I would love to see more of the other places, but I'm simply not seeing where you'd get the plot for a self-sufficient movie. So if anyone who commented yesterday wants to lay out a possible movie that's self-contained and would actually pull from what Tolkien said, I'd be very interested to read it.
I am a little concerned about overmilking the franchise, and I don't want this. I'm not anti-Jackson, but the pieces with true narrative potential all involve characters and types of situations he hasn't shown a great ability to do well. I'm only really concerned about that concern, though, when there doesn't seem to be a point to a further movie and they make one anyway. They're planning a fifth Pirates of the Caribbean movie, and that's built off an amusement park ride, for Pete's sake. And Tolkien packs so much backstory that there are definitely places worth exploring. (I can imagine four or five separate SiIlmarillion-based movies, though I'm not sure I'd want Jackson to make them...