Peter Jackson has now revealed something about who will be in The Hobbit which begins filming early next year in New Zealand.
Ian McKellen will indeed be back as Gandalf, and it is likely that various of the Elves such as Elrond played by Hugo Weaving and Galadriel played by Cate Blanchett will be making return performances.
Here is the link to the article and the MTV clip about all this.
tp://www.mtv.com/movies/news/articles/1627796/story.jhtml