[quote=@Descartes]
Can I ask what happened to the Boomers and Nellis AFB?

I mean; the Boomers didn't have an army; but surely with a working fighter jet and the know-how to pilot it, they must have at least done something to in someway protect themselves right?

What about the Brotherhood of Steel? They're also pretty well armed as well as mostly hidden.
[/quote]

If the courier chooses to aid the Boomers and the Legion at the ending of the game, Caesar elects to leave them to their own devices, and they do use the bomber to patrol their patch of the Mojave from time to time. 

As for the Brotherhood, there is an ending to New Vegas which was cut from the game but restored with a mod, in which Caesar allies with the Brotherhood, then turns on them and runs them out of the Wasteland.

For the purposes of this RP, we'll assume this is what happened to those factions.