The one thing we can agree on! Im sure that all fuels will have some limited role for as long as there are vehicles operating in adverse or unusual conditions. Hydrogen systems depend and will always depend on being adjacent to substantial batteries in the cars powertrain. This is because fuel cells can contain lots of energy but are much more limited in the rate at which they can offer that energy. In the mirai, the fuel cell keeps a battery topped off. When the car needs to accelerate quickly it draws charge from the battery.