There is mature technology that can be applied to hydrogen transportation, that is a minor Engineering challenge. A slightly bigger challenge but still perfectly doable is the conversion of all existing vehicles including ICE, that will give fuel systems Engineers some work for a while, but it's all doable given the money, and I described where the money would come from, so it's up to us if we want to do it or not.
Like I said it meets all stakeholder concerns. How are planes to be kept in the air by batteries? That is a pretty big concern that there are no technical solutions for, it just isn't possible to get the power to weight ratio needed for aerospace from batteries.
But it can be done with hydrogen, even Rolls Royce have shown it.
The same Rolls Royce as might anticipate their engines back in planes like concorde. It doesn't seem too much of a stretch to imagine supersonic flight back on the cards, this time also for ordinary people, in that new positively funded energy paradigm, just one product of a second energy renaissance.