Which fuels and processes succeed and which fail will be determined in the future, based on future technologies ans markets, not on history. We do not know yet that hydrogen and ethanol will succeed or will fail.
True, only time will tell. However, chemistry, and the potential energy of various molecules, provides several clues about what that future might hold.
Hydrocarbon molecules offer BY FAR the best combination of energy density, practicality, and safety as a storage medium for hydrogen. And compared gallon for gallon to, for instance, liquefied H2 in dewar container at its critical temp and pressure (-400F, about 200 PSI), the $5 Walmart red plastic container holding $2 to $5 worth of gasoline actually contains more than 50% MORE HYDROGEN than the pure H2, and almost FOUR TIMES the potential chemical energy!
Still, H2 might make some sense IF it were freely available
- but it simply cannot be found in that state, on this planet, in more than trace amounts, although we literally have OCEANS of the oxide covering more than half the Earth.
Ethanol comes closer to a realistic substitute, but again, it loses on energy density and cost. And as I stated before, NOT for aviation.