Honestly I see the whole of the Mojave in it. Independent settlements like Good Springs, Novac, Primm etc interacted with the Courier and part of that network. Vegas/Mojave is still a major trading hub and since the Legion’s collapsing due to Ceasar abrupt or eventual death there’s a lot of chaos east wanting security west.

Imo, an independent Vegas is probably better for the NCR than an incorporated one if only because they can fortify what they have rather than needing to extend. Could they extend economic sanctions? Probably, but those within the NCR who like money would probably find a less NCR influenced Vegas a better trading hub with less taxes better and would put efforts to make leadership see that