You've nailed the basic problem with hydrogen, which is why other sources are being actively looked at, like bio-diesels from algae which Boeing were looking at.
Using algae to produce fuel gives you a pretty limitless resource (given adequate area for farming vs food), but at present the fuels produced suffer from high viscosity at low temperatures, so may well need some further blending to produce something suitable for aircraft use.
Whatever comes in the near future is going to need to be pretty similar to avtur for ease of use in existing aircraft and supply infrastructure (which would be massive for hydrogen).
Presuming that no way of storing electric charge well suddenly emerges and solar and ground based laser power aren't sufficient, I'd place my money on something you can grow.