Wrong, utterly utterly wrong.
Nope. I happen to come from a universe where The Hobbit
is a relatively slender book compared to any one of LOTR's three parts. No amount of reframing the argument can fully lead away from that. I also come from a universe where less happens in The Hobbit
for a number of reasons, not least of which is it's pretty much entirely just about Bilbo's quest (while LOTR branches off from Frodo).
But once the choice was made to tell the story in the third person (like Lotr), to have events take time to actually occur, to show the passage of time and getting from place to place. You are looking at a long story.
But I'm not looking at a trilogy
. Hell, Jackson
wasn't looking at a trilogy until recently. I think you can make a pretty plausible case for the Hobbit to be a three-hour film, and this is for part of the reasons you suggest here - the ability to plausibly expand the setpieces of the novel. And three hours of course would be longer than FOTR was in cinemas.
But past that point you're going to start just draaaaging material out or throwing in bucketloads of Appendices (which, obviously, Jackson plans to do). And even with those Appendices, you're not dealing with the sheer breadth of material that FOTR, TTT or ROTK had to draw on.
Can he pull it off? I hope so. Is it entirely sane to doubt that the director of King Kong and the Lovely Bones may not get things to work? Totally.