I'm guessing that Movie 2 will climax with Smaug, and Movie 3 will intercut the Battle of 5 Armies with the Assault on Dol Guldur. Personally I'm more interested in seeing the White Council in action that the actual ending of The Hobbit
Though there's a rumor that Smaug's actual death scene will be cut from the ending of Movie 2 because it took too long to end the movie. They're gonna put it in the opening of Movie 3 instead, though there's another rumor there's going to cut that too because they didn't want to spend time on the Movie 2 villain in Movie 3 and will just stick it on the Extended Edition
How will they portray the Necromancer? The LOTR films took the interpretation that Sauron did not have a physical body. But in the books Gollum says that Sauron has four fingers on his hand, which means he does have a physical body.
So will the Necromancer be a Man-In-Armor, or a talking ghost form?