Non-starter? It's the actual grid battery storage solution a decade from now. EV owners will be able to pull and push electricity to the grid, incentivized by $. When the grid needs base load, $ paid to EV owners pushing electricity to the grid will keep rising until market equilibrium. Users can get notifications on a mobile app for certain $/kwh they'll be willing to receive to have their car go from 100% -> 60%, especially as battery storage gets larger and many people end up with 400 mile capacities where 90% of the time they use 50 miles during the day. Have a long trip coming up? Don't push electricity those days...
Especially with WFH (charge EV during day, give to grid at night, end up making $)
Also I suspect private car ownership will dwindle as full self-driving replaces human drivers. In this world (10-20 years from now) future-Uber will own fleets of self-driving EV taxis. The company will derive additional profit from acting as grid storage.
It's a non-starter proposition.