Back to aircraft, the hot subject in car propulsion is fuel cells, with all the big companies pouring zillions into research.
These run on hydrogen, either directly or, as at the moment, by obtaining it from methanol. It's not just for cars either, you can make huge ones for power stations.
Sooo.. I think propellers will be making a comeback, attached to fuel cells. Commercially it makes sense, as I believe
that a prop can go very nearly as fast as a modern airliner, so flight times and the like wouldn't be drastically affected.
The storage of the hydrogen is a prob as nobody wants to do a Hindenburg, but when I was at uni there was lots of research going on into this too, with cunning ways of trapping it in metal matrices and the like.
Or the aeroplane might have been rendered obsolete by teleportation
