If V2G ever makes it to market, I still think the most it will entail is delayed charging. There's enough concern over batteries without adding the extra cycles to backfeed the grid.
Of all the systems I've seen, I still think Mitubishi's M-tech Labo is the one done correctly. It's basically a battery-based RE system with the ability to parallel the car with a stationary (preferably a 2nd life) battery, so that the car isn't the only battery in the system. Even then, I don't believe any stored power is backfed to the grid and is only used to during grid outages and high demand.
I wonder if ChargePoint Home can integrate enough with the Nest (it already does to some extent) so that if A/C or electric/heat pump heating kicks in, it pauses EV charging until HVAC turns off. The 2.5 ton A/C unit at my house uses a little more power than the car does at level 2, so swapping one for the other would only be a few hundred watts difference. The Nest could signal the CH Home that a call for heat or cool is pending EV charge pause. The CH pauses charging, then tells the Nest to engage HVAC. When the call for HVAC ends, the Nest can signal the CH to resume charging.
"Bear" - 2012 Diamond White Pearl ES with QC - 2/21/2013
"Koorz" - 2012 Cool Silver Metallic ES with QC - 1/5/2015
"Photon" - 2017 Bolt EV LT in Orange with QC - 7/31/2017
Solar-powered since 10/10/2013