Then you have Vegas which will have the purchasing power to scavenge all important pre war tech House needs to maintain the city, evidenced by the Platinum Chip. Also Vegas will have enough revenue to continue to buy all the goods they need from the NCR. Further with House maintaining the Dam the Mojave and California will receive all the power needed to save the NCR from a Food crisis.
If the Legion stands they would more than likely re consolidate their hold on their current lands and spread north and south into the tribal and anarchy filled waste. I hate the Legion in comparison to House or the NCR. But they are a better alternative for wastelanders than tribals and bandits.
So we have California, Oregon, Northern Nevada, and Baja all industrializing under a functioning capitalist democracy. Then Southern Nevada is a series of prosperous towns and a major city all with standards of living about the same if somewhat less as high as Shady Sands (due to refugees from the NCR coming and driving down wages, no potential for industrialization and high transportation cost on all goods coming in from the NCR.) minus political rights.
Lastly there's Arizona, New Mexico, Southern Utah and Southern Colorado all under a generally hands off totalitarian state largely focused on external affairs with a standard of living on average about the same as Goodsprings minus any security threats and political rights.
Honesty that's not all that bad all things considered. Then adding in the 'good' ending of Fallout Tactics (Good Reputation, the warrior sacrifices themselves) then we have the whole Southwest, West Coast, and Midwest safe, secure, harmonious and in some cases industrializing. I don't really think that's a bad thing per say. When you add in D.C, the Pitt and the Commonwealth America is on the fast track to prosperity again but that doesn't mean the whole country is back to life. You have the Great Khans trying to civilize the Northwest, the Lonesome Drifter notes there are coal mines in Wyoming so something is going on there, and the games haven't even touched the American South outside of Point Lookout.
So let's let the rest of the U.S. redevelop now those stories have been told. But don't worry there is still more than enough material and ground to cover.