We no longer live in a past-is-prologue world. Now we live in a if-the-business-plan-works world where human inertia is no longer a big factor. All of the discussions below assume that most cars will be personally owned. My guess is that most passenger miles and commercial ton miles will be logged by robotaxis and robotrucks in the near term (five to ten years) because the convenience will be so high and the cost so low. The robotaxis will have smallish batteries and will charge often, but the charge stations will be more centralized and will be fed by small utility pv installations dotted around the periphery of the city and yes, these same robotaxis could be used for load balancing storage, but I suspect that their used and/or obsolete batteries will provide the storage.