There's also potentially big advances to be made in single use but easily recondition-able aluminium-air batteries due to an expanding market. An anecdote I've heard is a lot of R&D is focused on these at the moment as they have a higher energy to weight ratio compared to lithium chemistries so are idea for "disposable" use cases such as suicide bomb drones. There's also the more pedestrian idea of automated battery swap stations.

On a similar note, thermal imagers have got shockingly cheap recently, 50KPixel cube camera modules are available for <$200 and <$800 for the 0.33MPixel version. I recently picked up an integrated module with a 24x32 pixel sensor, LCD, uC and LiPo for £30n and it can "see" someone step out from behind a wall at a distance of 3 meters, ideal for my use case (airsoft!)