It's not just about runway length. Noise reduction would also make it easier to use smaller local airports. Electric aircraft are already more quiet, but there's probably room for even more reduction by using ducted fans or toroidal propellers.

We may also see a return to more of a hub-and-spoke model. Fly from a smaller, local airport close to you. Fly to some hub near the half-way point, switch to a plane that takes you to a small airport close to your destination. If planes are smaller maybe security can be relaxed too. Total time spent travelling could be comparable to taking a direct flight with a large international airport further from your origin and destination. Then the aircraft doesn't need to be very long range.