Fallout: New Vegas & Fallout Television Series (SPOILERS FOR BOTH)
In the sixth episode of the show, we found out about Shady Sands' fall in 2277. Four years before New Vegas starts. This retcons New Vegas. No one in the NCR talks about how their capital got nuked in NV. In the quest You'll Know It When It Happens, the president of the New California Republic visits the Hoover Dam. Why would the president visit the dam after the capital got attacked? Hell, why is the NCR still in the Mojave Wasteland? It doesn't make sense. So yes the show does retcons New Vegas.
IGN had an interview with Todd Howard and brought up the confusion and he said the events of New Vegas are canon and that Shady Sands was bombed after 2281. The sign outside Shady Sands in the series also refers to it as the first capital of the NCR, which would imply there's at least one other.
I think it's somewhat ambiguous. It lists the fall as 2277, but then there's an arrow to the mushroom cloud. So it doesn't say it was nuked in 2277, but it doesn't actually say when the nuke occurred either. But Todd Howard says New Vegas is canon and the nuke came after, so that pretty much answers the question, doesn't it?
Sorry I'm late to this, but the board suggests the destruction happened some time after 2277, not that it happened in 2277. The fall of shady sands apparently is before the bombing.
Where does it say the whole NCR is gone overnight in 2077?
The only thing that’s making you think this is a drawing on a blackboard that says shady sands feel in ‘77, and then an arrow pointing later on in time to a mushroom cloud with no date under it.
The NCR was the size of modern day Germany, albeit probably with a smaller population. If Berlin were nuked today, and only Berlin, do you think Germany would just collapse completely within 4 years? They’d just ignore lines of succession and all of their other cities and give up? Why do you think the NCR would just throw in the towel after losing one city.
As for why we don’t see many people besides criminal types, do you expect to see well adjusted people living next to the literal crater that used to be a city? The cast barely covers a few square miles around a recent nuclear disaster, it’s perfectly reasonable that they don’t see a whole lot of government officials and upstanding citizens while trekking through what amounts to a post-post-post apocalypse Chernobyl exclusion zone.