Yeah, great idea, lets go to a place that we've seen before in the series that has only had around 40 years to develop. I'm sorry, but if we were going to return to an old location, it should be from FO1, where they have had over 100 years to develop.
reno was around in FO1. you just couldn't go there. learn some backstory about reno, its been ruled by tribals turned crime family for a looooong time. think old-world italy and how the first organized crime rings formed. the early mafia, etc. that is similar to the environment of reno.
however in NV the van graffs have taken over not one but TWO casinos in reno, meaning that the place itself has to have changed GREATLY. obviously the architecture would remain the same (oh commercial row, i will miss the days of pk'ing on multiplayer shards there) but the dynamic and the feel of the town would have changed.
HOWEVER....
they need to make the fortress, and the boneyard. more specifically... the boneyard. it needs to be an enormous playzone filled with decrepit skyscraqers and empty buildings with nothing in them besides bones and dust... and mutants and raiders.
i'd love to see the gun runners "military" force scrapping with the regulators, or raiders if they decided to resolve their conflicts. i bet that with the deathclaws gone the boneyard has evolved into a massive centralized economy area, complete with attractions and residential areas... and of course, the outlying areas filled with hostiles and destroyed buildings.
being able to explore the masters base and the church after the fact.. now that would be cool. but for some reason i am thinking it was destroyed. can't remember exactly how.