[dredmorbius]

Commercial heavier-than-air travel has a distinctly limited future. Perhaps 5 years, perhaps 20, but when liquid fuels are no longer cheap, it will go the way of the dodo.

The alternatives are lighter-than-air craft, where speeds of up to 130 MPH are possible in current designs, it's unlikely that we'll do much better than this. These have _vastly_ lower energy requirements, and could be feasibly powered by solar cells plus either batteries or a small hydrogen fuel reserve capacity, or perhaps wholly by hydrogen-fueled engines, as the volumetric constraints of an airship are much lower than that of a HTA craft.

Or you could offer high-speed ground travel. Conventional high-speed rail is one option, the Hyperloop would seem to be another. I suspect that conventional HSR could achieve higher throughput -- 840 passengers/hour would be about 16 x 60-passenger rail cars. HSR offers lower speeds and longer transit times (2h 38m SF-LA projected), but might also serve more end-points for a roughly equivalent door-to-door trip time, though I suspect that's pushing feasibility. Musk discusses 2 minute to 30 second headways between pods, which is ... pretty aggressive (that still puts between 5 and 24 miles between pods, but you're moving at 700 mph top speed).

Either way, planes are going to be excluded by and by.