For those who've never been to Vegas in the real world, it's a bit surreal. It's a giant city in the middle of serious, serious desert. To the west some distance -- 20 miles or so, I think -- you have Primm. There are mountains along the north, and south of Vegas is a big patch o' desert with more mountains beyond.
In our modern 21st century, Vegas had a huge housing and construction boom right before the market crash in 2008-2009. This means there's a ton of sprawl in the form of new houses to the west and south. The Lake Las Vegas project created a huge man-made lake (with accompanying resorts, hotels, and golf courses) in 1990, but as of 2009-2010 all three golf courses have closed, the lake project company filed for bankruptcy, and there are leftover unsold houses all over the place.
Runoff from urban development and the lake itself has engorged the Las Vegas wash and overwhelmed much of the wetlands area. Parts of the desert south of the city are now a sump, with so much groundwater lost from the system that the humidity has become swampy.
Of course, before all of the modern development -- say, in the '50s -- Vegas was much smaller, dominated primarily by ventures in hotels and casinos funded by organized crime figures such as the infamous Bugsy Siegel. Vegas had already become a rail hub and the construction of the nearby Hoover Dam had brought some industry to the town as well. The "legitimacy" of casinos as businesses wasn't established until the '60s when Howard Hughes showed up to purchase a bunch of hotels, which prompted other corporations to become involved in buying up casinos as well.
So, future Vegas through the lens of the '50s -- maybe a sprawling oasis in the middle of the desert, creaking under the weight of its infrastructure limits. For all that people may have objected to the crime families in New Reno in Fallout 2, New Vegas would, if it comes from the '50s idea of Vegas, be heavily influenced by crime syndicates, famous underworld figures, performers, and jet-setters as well as corrupt union-oriented construction companies. After the bombs drop, though, who knows how such a place would realign itself . . .
(Boilerplate: I'm not working on F:NV. I don't actually know any details. I'm speculating like any other member of John Q. Public.)
