Not going to happen.
1) People will want their cars to have as much of a charge as possible, ready to use. They won't want to decrease that range by feeding it back to the grid.
2) EV owners don't want their battery life decreased by frequent cycles of charging and discharging. Battery life will be reduced to a few years because frequent cycles reduce percentage of range, and EV owners will be pissed.
I know what you’re addressing, but vehicle batteries aren’t going to go to zero because they are charged up once per day.
If you’re going by the 80/20 rule, you can extend those batteries out considerably longer than the normal life expectancy also.
Vehicle manufacturers are guaranteeing the life of the batteries out 8-10 years, and commuters aren’t complaining about batteries dying off.
People work about 220 days per year. I’ve forgotten the exact amount.
We’re not talking about the power company taking the full charge either.
As for people needing all their charge, they will know how much they need. They can sell the extra.