Well who said that density will increase forever? Only HH himself quoting someone unknown. So he can go to town on himself I guess.
Much more energy in a fuel tank than a Telsa battery pack now. A full tank of fuel is about 1/5th the weight of a Tesla battery pack. And the Tesla uses the potential energy more efficiently. It's going to be looooooong time before batteries reach the energy density of a tank of petrol. And they most definitely won't have Li-ion electrolyte.
