Now we're not sure yet if this scene will be in the AUJ: EE or DOS. The WETA Chronicles book features the High Fells, but then we have Peter Jackson recently talking about Gandalf exploring tombs in DOS, which might be a reference to Dol Guldur or the High Fells.

Perhaps I'm the last one to realize this (apologies if so) but today I remembered that we see Gandalf in the High Fells in the second trailer, which arrived in late September, just two months before the final AUJ was cut. Now we know a lot of Gandalf in Dol Guldur will be in film two, but since this trailer would have been put together AFTER the decision to make it three films, surely Jackson would have already decided in the main what would end up in film one and in film two? Tthus the second trailer does not feature shots of Gandalf in Dol Guldur fighting Thrain, or anything after the Carrock, for example.

This to me suggests that Gandalf in the High Fells was meant to be in AUJ and thus will probably be in the extended edition rather than moved to film two. That the WETA book appeared in December and features only things we see in the film and confirmed for the extended edition (Old Took's party, the Hobbiton marketplace, etc) corroborates the idea.