Lightweight containers for LH2 have proven so trivial as to have already been in use for many decades aboard space launch systems, which are even more sensitive

Lightweight containers for LH2 have proven so trivial as to have already been in use for many decades aboard space launch systems, which are even more sensitive to weight than aircraft. Aircraft LH2 tanks would want insulation usually omitted from rockets, but insulation is mature tech. Weight of LH2 is so enormously less than kerosene that, once LH2 aircraft enter a market, no kerosene airframe could continue competing. Given the low volumetric density, such that LH2 tanks would not fit in the wings, they will probably instead be removable nacelles slung under wings alongside the engines. This has the further advantages of eliminating need for mobile hoses and for complicated onboard plumbing. I doubt anybody would want to fly with inboard hydrogen tankage, anyway. Probably cargo craft will be first to use LH2, because carriers cannot load on another 40% more passengers just because the fuel weighs so much less.