Moore's law for batteries
A few years ago, batteries got about 20% extra capacity per year while the price dropped 20%. These days, the capacity figure is closer to 5% per year. The price reduction is harder to estimate because battery prices are now mixed in with fire bomb prices.
Physics limits battery energy density to about three or four times what you can buy today. Electric motors are about 80 to 90 % efficient, so room temperature super conductors, magnetic bearings and all possible advances in tech only get you another 25% at best. The complete board is 10kg. If we split that 50/50 for batteries and motors, and use magic massless motors, we can double battery weight and get to a theoretical limit of almost an hour in the air.
The big problem with the hover board design is it moves a small area of air very fast. You can get the same thrust for less power if you move a large area of air slower. At a guess, the model jet engines mentioned above use low temperatures to simplify the design, reduce maintenance and use cheap materials. Engines on big aircraft push cold air through the inside of the turbine blades made from high temperature materials so they do not melt. This allows a higher combustion temperature, which improves efficiency, so better power to weight ratio and less fuel used.
If you design a small turbine with similar features to a big aircraft engine and use it to spin a big propeller, you get a
helicopter hover board that can fly for hours with existing tech. (Also requires a pilot's licence, regular maintenance and a really big bank balance).