The question is, is northern VA strong enough on its own to carry the state for the Democrats? It's getting there, but not quite yet in my opinion.
Northern Virginia has become more like Greater Boston than like Greater Knoxville. Democrats can win Virginia based on a coalition of government employees in northern Virginia, similar types in Greater Richmond, and blacks in all economic strata. Virginia, like Maryland, has a very large black population. Politically it is becoming an upscale version of Michigan.