SW Virginia is still very Southern, but more Mountainy Southern (like North Georgia and Western Carolina).
That is true. I never hear what I consider to be a Southern “accent” here in central Virginia, and of course, there is not a whiff of any Southern speech in northern Virginia (a definite Yankee enclave).
Those two areas of Virginia cannot be considered as part of the South, IMHO.
As an aside, when I lived in the True South we never thought of Florida as being a Southern state despite its obvious geographic location. The Panhandle was an exception, we concluded.