Our problem isn't really suburbs shifting so much as it is urban areas taking over what used to be suburbs.
Nah trust me, that's the problem. Just take a trip on Google Maps and you'll see that NoVA is nowhere near as dense as DC. Republicans used to at least dominate in neighborhoods with McMansions while keeping it respectable with the slightly more dense suburbs, but those days are long gone. I think what you're failing to understand is that NoVA suburbs are much more educated and diverse where everyone knows a fair amount of minorities in their lives. This is not analogous to other suburban areas that still vote Republican.