New insulation technology changes the balance. Practical aerogel production means that heavy, shape-constrained high-pressure tankage is no longer needed, so that tanks may now be light and have the most convenient shape.

Furthermore, recent advances in catalysts for hydrolysis, some directly from sun exposure with no detour through electric form, make production of hydrogen from water and light practical.

New airframes with lifting-body designs, already better than those used now, have more room for tankage as a side benefit.

The practicality of any idea can change very, very rapidly, as details of solutions to engineering problems change. Recently solar and wind power were impractical. Now they are cheapest, and coal-fired power is impractical.

Is anybody building a plane that makes use of these new technologies?

No. At least not that they are telling anyone about. But there is plenty of evidence people equipped to do something are thinking about it.

Others have concluded that it doesn't make sense even with future technology. The energy density of hydrogen, while better than batteries, just isn't worth all the headaches.

For a similar cost to an extensive LH2 infrastructure, various diesel-from-air solutions could produce simple non-cryogenic hydrocarbon fuels. (CO2 + H2 = CHC + O2)

Yeah, I think hydrogen is a few decades too early. Maybe if there is real regulation limiting GHG emissions or high oil prices hydrogen will make sense, but until then I don't see how it can be made to work.