It seems way more likely that someone will figure out the technology (or already has) for a clean way for aeroplanes to fly, rather than change everyone’s behaviour to live locally and take the train to Italy.
Airlines have been trying for a long time to demand more fuel efficient planes as it saves them a lot of money and to a certain extent things have been improving but for medium-long haul flights it is hard to get away from fossil fuel due to its energy density
It seems way more likely that someone will figure out the technology (or already has) for a clean way for aeroplanes to fly, rather than change everyone’s behaviour to live locally and take the train to Italy.