This would require quite a bit of hardware on both cars and houses to work. And in many ways doing both backup to the house and being able to feed into the grid

This would require quite a bit of hardware on both cars and houses to work. And in many ways doing both backup to the house and being able to feed into the grid is pretty damn hard. So I will be surprised if this happens on large scale. This is an idea that sound great on paper but there are really a lot of practical issue between where we are now and in this ideal future.