Man, I hate finding threads late..... stoopit Christmas! Stoopit deadlines!!
A few thoughts....
I think it's jumping the gun to ASSUME that the second HOBBIT film will be all new material. I personally think what is going to happen is, THE HOBBIT will be told, as the book begins & ends, over the course of the two films. THE HOBBIT will be cut in twain, as they say, and things like the White Council and Gandalf B&E-ing into Dol Goldur will be expanded to fill out the films.
As for the White Council & Dol Goldur/Necromancer stuff not being essential, well, it is and it isn't.
Tolkein didn't write about them in THE HOBBIT, but there are bits of them in other books. Many things from the LOTR films were culled from the Appendices and other writings. Aragorn & Arwen's romance, for one.
As for what Tolkein did & didn't bother writing being the determining factor, please bear in mind that the Death of Boromir, arguably one of the most powerful moments in the films, was never in the books. Boromir dies, "offscreen" as it were, in between the FELLOWSHIP and TWO TOWERS books. So, there ARE precedents...
As for whether or not we really NEED the White Council and and Dol Goldur stuff, my tiny vote is "yes". Gandalf is a major character in THE HOBBIT. When Bilbo and the dwarves get to Mirkwood Forest, Gandalf (apparently) heartlessly abandons them, only to show up in a deus ex machina style at the Battle of Five Armies finale. In a children's book, it's OK to overlook this, but I think that in a major motion picture, audiences will sit and wonder "Why did Gandalf leave? Why isn't he staying with them?" I think that it's kind of vital to make sure that the audience knows WHY kind old Gandalf the Grey just lets the little guys go into the Worst Forest in Middle-Earth with nothing more than a "I have pressing business south! Cya! Wouldn't want to be ya!"
Finally, THE HOBBIT has always been a film that has going to be made. It's a fact. The LOTR films made TOO MUCH MONEY for THE HOBBIT to not ever see the big screen; too much money is to be made.
So, seeing as how THE HOBBIT is an inevitability, I think that Jackson's involvement is a sign for optimism. If THE HOBBIT was going ahead WITHOUT Peter, Fran, and the rest, I think we'd all have a lot more to be worried about.
C'mon! Come out of the Bitter Barn and play in the hay! We all get to go back to Middle-Earth soon!
Best post on the subject and one I agree with 100%.