And during that speaker series event, the CPUC chair said that "it will not take that long after this meeting." California also has a battery storage mandate of 1.3GW (of the top of my head) by 2020.
I don't see why focus on 8kWh batteries. I am still waiting for that elusive $100/kWh cost that Elon said would happen by 2022. Start making 100kWh batteries for $10k, sell them for $20k and bypass the grid completely.
That is the future...