There are niche applications that are already viable for electric airplanes. Harbour Air should have their electric Beaver floatplane conversion in commercial service this summer and several Canadian flight schools are in the process of introducing electric trainer aircraft for PPL training. There is huge money being plowed into battery development so it is reasonable IMO, that we will see viable small short haul electric commuter aircraft in the next decade.
https://en.wikipedia.org/wiki/Gartner_hype_cycle
We are in the very early stages of electric development and I expect it will follow the trajectory of most emergent technologies