V2G is nice in theory, but I doubt it'll be popular for a very long time.
But smart throttling is handy. Basically controlled load 2, but maybe with a few extra bells and whistles. Curtail charging when the local power grid is stressed, or during peak usage periods in general, or when you think there's going to be a massive surplus shortly (e.g. dawn with clear sunny weather forecast) but leave the electrons to free flow at other hours.