I too believe that modular energy blocks are key to price and technology competition. But tech vendors really don't like competition, so I doubt that this will be a reality unless forced by regulators.

Regular batteries began to be standardized in 1928 by American Standards Association (predecessor to ANSI) - according to Wikipedia. We can buy standard batteries in a variety of sizes. I envision a "modular energy block" as something much bigger than these "C" and "D" batteries. But small enough to still be picked up. Perhaps 40 lbs.