Flash charging is 1MW - 1000V, 1000A. That peak power has to be provided by the grid or some energy storage that can be replenished in time for the next cars. We need cheap and smallish batteries (because burying is not always an option) to be able to install that much storage and peak power output in the MW/MWh range all over the place. We'll eventually have this but we might be talking in decades rather than years.
Or, why not, maybe we need fewer cars.