An anonymous source stated that some of the main sticking points include amendments to Peter Jackson's and GDT’s contracts requiring an additional 3 months of principal photography, and temporarily suspending some of their other projects.
The insider also mentioned some legal wrangling with the Tolkien Estate to acquire additional rights to materials not currently under license which would provide the bulk of the plot for the third movie. What specifically this could be is a guess. The source seemed to imply it may be delving into the back-story of the Istari (Wizards) including Gandalf and Saruman’s youth in Valinor. The inclusion of other young wizards at the academy would provide an opportunity for cameos from LOTR actors who’s story arc doesn’t fit into The Hobbit. The latter would go a long way toward explaining recent cryptic quotes from LOTR actors about possible appearances in The Hobbit. GDT's fav actor Doug Jones (Pan's Labyrinth, Hellboy) is rumored to be cast in The Hobbit.
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TheOneRing.net CONFIRMED THE HOBBIT TRILOGY WAS AN APRIL FOOLS JOKE! SORRY NO TRILOGY.