http://www.gamebanshee.com/interviews/105885-fallout-new-vegas-and-dlc-post-mortem-interview-part-two.html
By Chris Avellone
So in terms of Fallout lore I have come to the understanding that Obsidian because of Avellone has decided that the cannon ending of Lonesome Road was the complete nuclear destruction of the NCR and Legion to reset the West Coast lore.
On the one hand I can not say I disagree with the idea. The NCR is basically on the edge of a new industrial revolution with Vegas or without, the Mojave if NCR/House/Good Independent ending only speeds up that process. The Legion lands according to J. E. Sawyers formspring are so good that...
Did you catch the bit about "power" flowing consistently? We are talking about a standard of living that billions of humans today do not enjoy even in Legion territory.
When you add in the post scarcity technology from the Sierra Marde I would LOVE to see the West Coast Fallout factions nuked. It gives the series a chance to give us a Fallout 3 experience that actually makes sense and halt the continued progress we have seen in, especially from the NCR with its manufacturing, working power armor, vertibirds, railroads and of course electricity production. Shady Sands was already pretty nice in Fallout 2, with other places like Vault City and maybe San Francisco under NCR control things have gotten a bit to comfortable.