So? We don't know what we don't know. We might find some way to store energy within chemical bonds like fuel (39,405 Wh/kg limit of liquid H2) or nuclear (8,700

So? We don't know what we don't know. We might find some way to store energy within chemical bonds like fuel (39,405 Wh/kg limit of liquid H2) or nuclear (8,700,000,000 Wh/kg of Pu-239) or matter-antimatter interaction (24,965,421,631,578 Wh/kg). Current lab records of 1000-2000 Wh/kg are just a start, we're far far away from hitting any limits.