So with the trailer out, any predictions on what we might see in the movie?
I think PJ will try to tie some things with the LOTR movies. I predict that it will show the beginning of the secret alliance between Sauron and Saruman. Maybe, Saruman purposely let's Sauron escape Dol Guldor?
I think not Glorfindel, Saruman is going out there for a meaning. Remember the appendices in the back of the ROTK, Saruman was anxious to drive out Sauron from Dol Guldur only after the present known area of the Gladden Fields was the were the ring was. Saruman wanted the ring for himself, in order not to let Sauron have it he would need to take it, so..... that's my prediction for Saruman. And what the heck are those troll thingies that stomp of the ground, is PJ going a little nuts?
Yes, I remembered that about Saruman and Sauron, but you have to keep in mind that this is the movie. PJ really tries to connect this trilogy with the better trilogy, the LOTR, with "canon/noncanon" materials. Also, going by the movie universe, there wasn't much evidence indicating that Saruman had plans of his own. The only thing on top of my head that I can remember was that Saruman sent a band of uruk-kai on a somewhat "secret" mission to capture the hobbits, knowing that one of them had the ring. Even with that, Saruman still continued with their plan. They had a strong and cooperative, even to a certain degree, trusting alliance, compared to Gondor and Rohan.
In the trailer, to me, it seems like Saruman wants to be alone with Sauron. Knowing that he has the two most powerful elves with him (Glorfindel and Cirdan having little to no roles in the movies), I think he is bright enough to realize that to have a better chance of driving Sauron out of dol guldor, it would be wise to have them by his side when confronting Sauron.
The trolls are there to "wow" the audience. It may also indicate that Sauron has a less sophisticated army and not quite ready or have full strength to dominate all of middle earth yet.
What if Thranduil dies? You never here about him in the LoTR so... he could die and fade out of the story. I don't think many people like him. So PJ will make him die a terrible death by getting stomped on by a troll, just a figure of speech.