I doubt it is the narrative that would have been fallout 5. Fallout 1 and 2 were developed by black isle studios in Irvine california. They chose to set the game in a post apocalyptic version of the local area. When bethesda purchased the IP and made their own version it was set in capital, literally where their offices are located.
The next west coast fallout, new vegas, was developed by obsidian, also based in Irvine.
Both fallout 4 and 76 were both east coast games based on locations pretty close to the studio that made it.
From the entire history of the series, Fallout has been set near to the studio that made it. Which is why I highly doubt the script was based on the notes of bethesda's next fallout.