I love your take on the region! You clearly know your stuff!
I will say, I don't think Fallout has to focus on anything Pre-War to keep its identity. A lot of the Pre-War elements in the older games are important because of what they mean to the wasteland now, not the world of the past. But there's plenty of interesting stuff to be explored in the Pre-War world, I just hope we see some more of the actual war and less Vault-Tec politics.
As for the NCR, I think we're just going to have to agree to disagree - for now. I've no intention to debate you on your knowledge of geography. I think your reasoning for the geographical depiction is well-thought out.
But that said, I feel like you're misinterpreting my problem with the show, which is that I feel it's not following the NCR to its natural conclusion. The NCR has concluded by the time we see it in the show - Hank nukes them in a flashback. What we see in Season 2 are a few remnants. The best we get showing the NCR's decline is the loredump scene in the schoolhouse.
The show is popular and will no doubt keep going, so there's time to touch on the NCR more, but my point is that it's not really showing the decline of the NCR, it's showing the decline of Pre-War America and having characters pay lip-service to the NCR. If the NCR is still out there, and they can tie their story to the Pre-War plot, I will happily eat crow. But as it stands, the NCR in the show is just a small prop in the inner shenanigans of Vault-Tec. Destroyed by Vault-Tec, with its remnants led by a Pre-War scientist.
I just think there are ways to write an allegory for the Pre-War situation without carrying actors directly from the Pre-War... that was a problem I had with Fallout 4 as well. Sure, Ghouls exist... but as we see with Cooper Howard, they're changed by the wasteland. A lot of the Pre-War characters in the show feel like not much changed in 200 years.
They also do a lot of talking on Communism and whatnot in the Pre-War scenes. I feel like if they acknowledged the fact that it's a resource war a little more, it'd be a lot easier to allegorize using the lack of resources in the wasteland. But I do think that's not a misinterpretation on their part, and more of an interesting take on how Pre-War America would have spun the war for the public.
Anyway, I like your optimistic take on how they could develop the region! You raised a lot of good points that have definitely helped me see your perspective. It's super refreshing to talk to you!