Probably you will want liquified H2. So, we need volume manufacturing of aerogel, for the tanks. If we don't go to wholly new airframes, we will need to sling the LH2 tanks in nacelles under the wings, like the engines, because the needed tankage volume won't fit inside normal wings. (With a new airframe with more internal space, the tanks could be inboard, but maybe you don't really want big tanks of LH2 inboard.)

The LH2 would be electrolyzed on demand at the airport, using power delivered by transmission lines from all over, banking LH2 when the sun is out or the wind is blowing, when it is cheapest.

Once these planes start flying, it will become impossible to compete with them, because the smaller mass of fuel needed translates to substantially more freight, both total capacity per flight, and per unit-cost of fuel. But there are still things to work out, so there will be an interim need to synthesize jet fuel from atmospheric CO2 and H2, which should soon get cheaper than extraction.

It would be helpful if somebody were to come up with a good use for all the waste oxygen everyone is going to be producing.