I know that some of the devs frequent this forum, and unless I'm mistaken it is neither debunked nor confirmed that the future DLC will take up the unused areas on the map. Many modders seemed to be discourgaed about making new areas in the unused space, as if Obsidian comes out with DLC that takes place in that spot, the mod will be unusable. So if a dev could enlighten us on this, that would be great, thanks.

Also, apologizes if this is already confirmed or not. I haven't seen anything saying it is.

I dunno, seems to be pretty mountainy. If you've ever been in that area of NV while flying on a plane, there really isn't much else there other than what has been put in the game. From 36,000 feet (well less cause you would be descending) in the daytime, its a little blip in the desert

But do we really need a confirmation of "this area will be used for DLC content" - modders do what they do at their own risk of collapsing with the upcoming content anyway. I'd see it - even though it seems obvious to use the unused space on the existing map - as spoiling a surprise.

i've HEARD that the unused space on the western half of the map roughly correlates to the general area of several major locations from the first two Fallouts. i'm too lazy to line up maps and determine if this is indeed the case, and i'm unaware of any existing maps pointing this out, but if this is true then it's likely that they'll wind up using most of it in DLC.

i'd recommend avoiding that general area for now. wait a year or so, maybe - there's more than enough underutilized space east of that for modders to go wild.

I can't think of what areas those would possibly be. Comparing maps by eye, the only places of note that are anywhere close to the empty space on the west of the map are Vault 15, to the north, and The Hub, far to the west.
There's nothing at all in that region.

EDIT: There is certainly nothing from either of the previous games there. On http://images1.wikia.nocookie.net/__cb20080606162927/fallout/images/2/29/Western_USA_v1.0.jpg, an old one that marked everything in each Fallout game plus areas from Van Buren, you can clearly see the mountain where Jacobstown is. With that reference to scale, you can tell there isn't anything in the region. in question.
I also compared in-game maps, and overlayed several locations from them on google earth to arrive at the same conclusion.http://tinypic.com/view.php?pic=2zozx4x&s=7
I should have marked Jacobstown. Ah well, too late now.

Even if a dev read this he wouldn't/shouldn't leak the information here.

i thought the north passage was going to be opened up for the dlc.

If I may ask, WHY did you think that? Did you hear a rumor or something?