i think it would be nice to get some new towns with shops and bars and new quests.something similar to rivet city.the only real town like that in new vegas is good springs and maybe primm .

Wouldn't really make sense for a town to just appear over night though.
Maybe if it's a hidden place like a society of around 30 to 50 ghouls.
But for a town like goodsprings or primm to just appear on the map would feel very strange.

do you mean a town just outside the vegas area added by a dlc cause if thats what you mean then that would be good

they could be moving to new vegas and setting up shop.or mabey unlock a new part off the map where the is towns.the west of the map is locked

yea thats what i would like to see

Yeah either they have to unlock part of the map for the town, or they have to place it as a hidden society or they have to place it as being "under construction".

The three thought locations for dlc entrances are ;Northern Passage , Canyon wreckage there's another but seriously dudes can't remember off the top of my head :sadvaultboy:
Although this wiki post pretty much confirms Northern Passage as a dlc entrance: http://fallout.wikia.com/wiki/Northern_passage
Also the next location is Utah so I hope there are settlements and small cities.

Not to the main game world, but with Honest Hearts, New Canaan might be a totally fleshed out town. Probably won't have bars though, those dudes are Mormon.

New Canaan is all but confirmed to be in Honest Hearts, they may have changed the Mormon part, though.