While many a many people are convinced that a Broken Steel add-on for New Vegas would cripple or ruin the entire ending to the game. However.
Bethesda and Obsidian could potentially create an add-on for Fallout: New Vegas that would resemble the same exact idea of extending the end of the game and raising the level cap. Adding new items and cool new features.
Before you close out of this forum topic in utter disgust, let me explain.
At the end of Fallout: New Vegas you will have had to choose 1 of 4 different directions. Four Different Paths to complete the game. Choosing to side with the factions of either NCR, Caesar's Legion, Mister House, or Taking Vegas for yourself.
A Broken Steel Add-on Pack would send players to anywhere in the world. It would start and end in four different paths. Say you chose to side with Mister House. This particular expansion would send you on an after-ending path to a locale in the world under orders from Mister House. If you chose NCR, Caesar's Legion, or Took Vegas for yourself. The same would apply.
It would most likely be the single largest DLC for any game on the market today. It would have to feature a full story line for 4 separate stories in total.
My personal idea would be after the Capture of New Vegas. This particular expansion deemed "New Territory," would feature 4 new story lines that carry on after the battle of the Hoover Dam.
Mister House: The courier, after helping Mister House upgrade his securitron army and winning the battle of the Hoover Dam, is sent on a mission by Mister House to the Great Divide. His mission is to seek out the rumors of the fallen Legate Joshua Graham. Attempt to make peace with him, and recruit his help in acquiring the help of the last troops of the Caesar's Legion. But along the way the NCR Rangers, Brotherhood of Steel, and Remnants of the Enclave are engaged in a furious battle for control over the southernmost point of the Colorado River.
NCR: After assisting the NCR with the second great battle of the Hoover Dam against Caesar's Legion, the Courier is tasked with the job of eradicating the remaining Caesar's Legion forces located near Moab, Utah. Upon arriving in Saint George, the Courier is thrust into a heated battle between the Brotherhood of Steel and the Enclave. The Courier finds that the factions are battling over a hidden Uranium-235 mine located underneath Saint George.
Caesar's Legion: Following in the footsteps of great legends such as Legate Lanius and Legate Graham. The Courier is tasked with the search for Joshua Graham. He is sent to the Great Divide in search of the fallen Legate. Upon arrival into the Great Divide, the Courier is thrust into a conflict between the Mormon Battalion, a large group of slavers called "The Aryan Brotherhood," and the Followers of the Apocalypse. They seem to be engaged in battle for control over the Great Divide.
Yes Man: Deciding instead to Kill Mister House, and take the Hoover Dam from Caesar's Legion and NCR. The Courier has taken full control of New Vegas. The straggling members of the NCR defect to becoming scavengers of the ruins located around the New Vegas Territory. The Courier has complete control of Vegas, but being urged by Yes Man to control more territory. The Courier is tasked to take a leave of absence from being the Mayor of New Vegas, and lead a small battalion of Securitrons to Cedar City, Utah. A place of much prosperity, a city completely unharmed by the nuclear fallout. Upon arriving in the Utah Desert, the Courier is engaged in combat with NCR Rangers, Caesar's Praetorian Guard, and the people of Cedar City.
This particular expansion would add new features such as a raise in the Level Cap to 40. New Perks, new companions, and new weapons and armor. Each path of the DLC would feature a very western style and design. Including the incorporation of rideable animals such as Bighorners, Tamed Cazadors, and Domesticated Giant Ants. New learning path incorporated with the DLC would venture deep into weapons crafting and ammunition design. Take the Path of the Leatherworker, Blacksmith, Ammosmith, or Gunsmith. Each learning new recipes to craft new armors, weapons, and craft unique ammunition!
(What do you think? I personally think this would be the only way to have a Broken Steel for Fallout: New Vegas. I've thought quite a bit about it, and this is a way to lead the Fallout Story towards a Great Divide Game, New Canaan Game, Phoenix game, or possibly even a Denver game. Constructive Criticism is preferred, but if you're blunt and want to give it to me rough. Go ahead.)
Jason Bergman has stated that one thing that will not be appearing in a DLC is the ability to extend the game past the ending!