Your comment about "nobody lives near a metro line" though - I mean, come on! With the orange line and silver line extension there are lots of places in NoVa near the metro. Yes, the car traffic is horrible, but the car traffic is horrible in SF, LA, Boston, NY, Austin...
As another commenter pointed out, there is actually a ton of empty real estate in Crystal City itself and no doubt a ton of it will be built up as apartments/condos now.