Personally I suspect that the US Navy nuclear-powered CO2-to-JetA system, or something like it, will be the long term solution when fossil JetA becomes prohibitively expensive. Electric prop planes are feasible but electric jets really aren't.
So it is so strange and fascinating that Elon Must seems to think that it could be done.[1] Like: if we take todays lightest and most aerodynamic sail plane, add batteries and an electric motor, and it's still worse than a cessna [2] - how exactly does he reach the conclusion that electric jets, _vertically starting and landing_ jets, are feasible? I really wish for something like the hyperloop design-docs to explain the thinking behind it :)
[1] e.g. http://bgr.com/2016/02/07/elon-musk-electric-jet-great-idea/ - “Well I have been thinking about the vertical takeoff and landing of an electric jet a bit more,” Musk said. “And I think I have something that might be close. I’m quite tempted to do something about it.”
[2] MEA: https://www.iei.liu.se/machine/applications_re?l=en