Great stuff.
Well, the battery technology and the electric propulsion technology has advanced so much in the last 20 years that it's incredible, so it's not beyond the realms that in another 20 years we'll see workable technology. Compare that to the combustion engines who virtually have stood still since the 30's. At least in aviation. I just sent my magneto off for overhaul again and that damn thing has
not changed since the 30's, lemme tell ya...
Once again, I can only compare to the automotive industry and how lightning fast things have been going there recently in regards to electrics. Tesla's Model S is imminent for release, will cost $50K and have 300 mile range. Now that's going to be very competitive. Numerous other makers have similar offerings in the works. Just look at the recent Frankfurt Auto Show - every major car manufacturer has some kind of electric or hybrid thing going on, even Ferrari!
Tesla Model S
I don't think we'll be driving combustion engined cars in 20 years. In fact, if I ever buy a new car again it's going to be some kind of hybrid or electric thing. Not because they make more sense financially, but because it drives me nuts that my whole car is rattling, making heat, noise, emissions and burning fuel at a stop light... An all electric helicopter might take a bit longer, but I wouldn't discard some kind of hybrid by then.