I recently did a back-of-the-envelope calculation of the average daily electricity usage in the U.S. vs. the number of light duty vehicles. It came out to about 55 kWh. Of course deep electrification (replacing consumer fossil fuel use with electricity where practical) would push that up by 75% to 100%. If we go to a near 100% BEV for light duty vehicles while at the same time, increase range to between 400 and 500 miles (which appears to be the track), then our vehicles would have an average state of charge equivalent to about 1 average day of electrical use.
It seems to me that widespread V2G may eliminate the need for medium duration grid storage batteries. I think it is likely that with V2G we only need short duration stationary batteries, thermal batteries for industrial heat, and multiday duration batteries. There may be some need for seasonal storage, but HVDC transmission (which is getting more press lately) may alleviate that need.