Reston is a planned community, started in the 1960's. Among the compromises from the original plan was a downgrading of density; the developers discovered that single-family houses sold better than townhouses, which sold better than condos. Now as the town has aged, and as Metro approaches (arriving next year on the east side of town), there's more and more planning for redevelopment, tearing down old buildings and building new ones. In the process density is going up, which should make Matt Yglesias happy, if he ever travels from his DC apartment out to the wilds of Virginia.
Here's a post discussing planning for one of the redevelopment projects. What strikes me is the bit about "Transit-Oriented Development". It ties in with an observation about the Hunter Woods Fellowship House (an apartment building for seniors) which is served by a Fairfax Connector bus, although it probably adds 5 minutes to the bus route.
Seems to me in the near future it would be easy enough to have a vehicle, electric powered, controlled robotically, callable on demand, which runs only a route connecting an apartment complex like Fellowship House or the proposed Fairway Apartments to an express bus route or metro station. Because the route would be set, it should be a relatively easy challenge to do the robotics. By having a short route, the waiting time at either end would be minimal. By linking it in with a smartphone app, it could be response.