The technical issues of running future designs of turbine engines on hydrogen could probably be overcome quite easily by redesign of burners and combustion cans.
The real problem is the logistics of making hydrogen refuelling available at key airports, and to be able to do this safely.
There is also the issue of legacy equipement that will continue to use jet fuel.
I guess to be realistic jet fuel will be around for the next thirty years its just whether it is produced from alternative sources than crude oil such as biomass, gas to liquid technology etc.