With the fact that a century and change after this game's date the Brotherhood passed through on the way to DC (via a stop at The Pitt), and didn't have much to say about the trip being unusual, I'd safely say that this is non-canon. Probably ended up a wasteland like any other- small communities (many founded or at least including Vault 76 residents), but nothing wild and crazy- if there's anything even the size of Diamond City or anything like that I'd be surprised.
Something that jumped out at me: Vegetation. Fallout 4 has two-century-old dead trees everywhere you look, ditto for Fallout 3. (Vegas, of course, was saved from most direct hits by Mr. House, so its vegetation is much more robust) But here? 25 years after the bombs, this looks a lot like West Virginia as I've seen it passing through. Either this is an area that China just didn't bother with and that somehow was spared the worst of the fallout (unlikely if it has all these nuke silos for players to find!), or it took a remarkably long time for these forests to die off as they did in Boston and Maryland.
Should be interesting to see how they handle ghouls, while we're at it- the two century gap between the war and Fallout 3 and 4 means ghouls look pretty rotted (particularly in 3, they toned it down considerably for 4!). But only 25 years later? I wonder if there's going to be any addressing of the fact that ghouls look less-awful, or if 25 years is considered enough time for them to have become the ghouls we know and love (from a distance). For graphic purposes it makes sense to just use Boston's ghouls again, of course.