Never been to Blue Ridge myself but big black cats are one of those things that keep coming up all over, right? Similar sightings in Essex where I live - we've had "black panther" reports for years and the evidence pattern is remarkably consistent across different continents. Upright posture when observed, melanistic colouring, size estimates that usually put them well above any known domestic or feral.
What's your best estimate on the size of what you saw? That's always the critical detail people gloss over. Were you able to compare it against any fixed reference point - a fence post, a car, anything like that? Distance to the animal matters too because people routinely underestimate size at range and overestimate it at close quarters.
The Blue Ridge area is interesting because theres documented historical cougar habitat there and melanistic cougars, while officially considered extremely rare to nonexistent in North America, do get reported. Would love to know more specifics if you've got them.