There are several posts including sound and video, where Jackson mentions there will be an extended versions of the film, but that he wants to film more material if possible.
He has stated he doesn't know if (and thats if the studio even approves it, accountants already counting the cash) it would be even more material for extended versions or if it would require an edit for a third "Hobbit" film.
Technically he could even be talking more specifically about a bridging film (which at one time was actually considered for the "2nd Hobbit" film.
As opposed to the expanded Hobbit film that just features appendix material that happened during the same time period.
Now we already expect additional pickup shooting for the 2nd film to occur next year. Of which fine tuning of script still absolutely occurs. But usually it doesn't require something as major as creating a new ending point (to end a chaptered story). That would take a bit of real work, but its hardly impossible.
Personally I would love more appendix material (ie bridge material). But a lot of that (though clearly not all) I wouldn't want as part of the Hobbit film as they occur a significant amount of time later. But I would still love to see it, be it expanded home market material. TV specials, ect.
The key issue is how much material is he talking about and the associated cost involved. Why its almost assured that the Hobbit will make a sizable profit (It is possible it could flop, but I think its highly unlikely). But a studio is going to want to maximize that profit. With the Home market a mere shadow of its former self. It will be much harder for the studio to greenlite additional (above already planned pickups) large scale expenses. The easiest way to make a huge amount of money would be a separate film release in some form.
But until we have an idea of first the length of material planned for the 2nd film, current level of extra footage that would be about the 2nd film, and how much additional footage Jackson is talking about.
Then you have the issue of what material Jackson wants to film. Is it directly connected to the Hobbit and its specific time period and events? Or is it more of the bridging material that was originally considered a possible option for the 2nd film?
Certainly one thing is certain, its a complete 180 from what he felt about filming when he completed principal filming of LOTR. THough of course those were much more grueling filming schedules for the amout of material filmed.