Soaring in general seems like a ripe opportunity for automation.

If someone makes software that can seek out and make use of lift (using various information sources), it could pave the way for very low-energy drones.

EDIT: Interesting.... seems there is something already that handles the "circling and staying in thermals" part.

https://ardupilot.org/plane/docs/soaring.html

https://arxiv.org/abs/1802.08215 "ArduSoar: an Open-Source Thermalling Controller for Resource-Constrained Autopilots"