This is the first time I even partly may disagree with you. I'd say something like this: without a major technological breakthrough, not currently imagined, batteries will not become as cost-efficient as are IC's. Moore's Law no longer applies to IC's either now that nano-sizes are impeding further miniaturization.
I am very reluctant to say anything absolute with reference to science or even engineering. New developments seem often to challenge conventional wisdom, and I tend to quote Mark Twain "it's difficult to make predictions, especially about the future".
OK, fair enough, the IC world is nearing the edges of Physics of how densely packed chips can be, but there are a lot of other new ideas on the horizon that may continue the miniaturization for another few generations at least.
Even if there is a major breakthrough in battery density (there was a rumor thread here started by someone who had run into a Tesla battery engineer in a restaurant and was told a 500 KWh battery pack was in the works, though I'm skeptical of that), their development won't follow the development of ICs.
ICs are a very weird market. When a new, complex part is introduced, the initial yields are usually down in the single digit percents. This is one reason why the latest and greatest is always expensive. I've read that for most mass market ICs, a company can start making a profit at 7% yields. They throw away most of the rest. The PhD Physics types go to work trying to figure out why the new chips are failing and send their findings back to R&D. By the time a product is mature, yields can be up well over 90%. (I'm currently working on a test instrument used by the PhD types in their forensic analysis.)
Nothing else can have such high initial failure rates and still be profitable. By the time production of an IC is mature, the profit margins are approaching that of software. In both almost all the effort is put in up front during R&D and production can be very cheap.
I saw a talk given by JB Straubel on YouTube where he made the pint batteries don't follow Moore's Law. I believe most of the cost reductions in batteries comes from economies of scale and other more traditional production improvement methods rather than yields going up like in the IC world.
The Gigafactory promises to push down the cost of Li-ion batteries through a mix of economy of scale and vertical integration of production and physical proximity to the source of raw materials. I think it was Elon Musk who made the observation that the way Li-ion batteries are made today is very inefficient. Parts are sent back and forth (often between countries) before the final product is shipped across the Pacific to Tesla. Elon analyzes everything from the ground up and he saw that one large vertically integrated facility could make batteries 30% cheaper simply because things aren't getting shipped all over the place.
I think it likely that there will be some kind of major technology breakthrough with battery technology that will revolutionize the industry and push the cost per Kwh down dramatically while pushing the Kwh/Kg way up, but nobody is really sure when that is going to happen. It's possible that is has already happened and there hasn't been an announcement because they are still evaluating, or it could be 10 years from now. Nobody knows for sure.
I suspect a major reason the major car companies are dragging their feet getting fully into the EV market is because they are afraid of getting burned by committing to the best technology for today only to discover it's completely obsolete tomorrow.
