Electric airplanes are already used in training in Europe. They are less expensive to operate on an hourly basis just because of fuel/energy cost. But they are probably also cheaper to overhaul; the Emrax motors in Pipistrels are relatively simple, and it would probably cost less to buy two and swap one out (sending the other one back to Emrax for a new bearings) than to do one thermal engine overhaul. And almost no downtime!

(I work on another electric airplane which will take flight in 2023.)