EVs are in the very beginning of the technology adoption curve. It wouldn't make sense to deploy infrastructure for technology that barely exists in the market. I assume at some point in the future this will change and that V2G stands a good chance of being developed.
The Japanese charging standard incorporates V2G capability, and my guess is that v2.0 of J1772 will likewise incorporate a provision for sending power in the other direction.
If battery capacity gets cheap enough, people will be purchasing batteries simply to avoid using electricity from the grid when it's expensive, and perhaps sell it back at that rate.