Here's what will happen:
- They will cut the number of dwarves by 3-5. Getting down to a manageable number is key, although I think that the team dynamic of the dwarves is the emotional core of the story.
- Gandalf's role will be somewhat increased in terms of his prescence. By this I just mean that the story will linger longer at points where he is there, as opposed to cutting down the scenes where he is. They will want any connection to LOTR proper to be as strong as possible. This means keeping more of the Beorn scene than will be necessary, and spending more time in Rivendell with Elrond.
- The final battle will likely be seen to a much larger component than the book, however we won't see MUCH more of it. We'll see the fall of Thorin, we'll see the important story notes that we only learn about in hindsight really, but I think that when Bilbo falls the battle will not go on forever. It would be silly to do so.
- The most obvious place for cutting is the deneoument, aka anything after Smaug is shot. There is a bit too much time spent on the politics of it all and it slows things down. I still expect that to stand as the story's climax, if not the action's, but I think that they'll move from fall of Smaug to the battle a bit faster.
As for how they'll handle Bilbo, I'm not sure where I stand on that one...it'll be tricky, for sure.
