He says he's drawing upon lots of material from the Lord of the Rings appendices, which probably means he's taking a few lines here and there and making a huge story out of it. Since the Tolkien Estate holds the rights to Tolkien's other works like The Simillarion, Peter Jackson's best way of making more films set in that universe is to squeeze as much juice as he can from the appendices - which they have the rights to. So it's a workaround/loophole of sorts to getting at material which isn't restricted to Lord of the Rings and The Hobbit without having the actual rights to the proper, arguably better, stories. The Hobbit, which should really just be one self-contained film, is caught up in the middle of this. We'll end up with a continuous dragged out Hobbit story with scenes constantly cutting to a larger story involving the Neuromancer and Battle of Dol Guldur. If he didn't want to add all this extra material to the extended editions of the two Hobbit films, he could have just made the Hobbit film and then made follow up films which took place in that world, 'Tales from the LOTR appendices set in Middle Earth' or whatever. Either a rights issue with not being allowed to make a film that isn't called either 'Lord of the Rings' or 'The Hobbit' or they decided The Hobbit trilogy will allow for a stronger brand, coherency and continuity (or as Colonel. would put it, '$$$').
Still, I have faith. I loved the Lord of the Rings trilogy and if Peter Jackson retains that level of quality, then I'm sure I'll enjoy the films.