I think propulsion will be electric. 100% power at 10,000ft with no need for expensive turbo's - what's not to like?
They have been testing graphene based batteries which on a weight for weight basis hold 10 times the charge current batteries and could be charged in less than 30 minutes.
if they can make it viable under commercial conditions (battery lifetime etc) having something with a 700 mile range and 30 minute turn around is perfectly reasonable.
I don't see why ga planes can have more complex wings allowing for higher wingloading. why cant we have a plane with a clean 1g stalling speed of 90kts, add some leading edge slats, or droops or complex flaps or something so that a family of 4 cruising at 250mph / 10,000ft with a 160hp electric motor is expected rather than fantasy land