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A lot of it depends on NASA. Battery tech will never, ever be good enough for commercial flight but h2 cells might be.
Out in left field there's NASA's regular experiments with laser/wireless power beaming, and the recent interest in EHD (electrohydrodynamics aka ionocraft) vis-a-vis combustion engine flow control gives a clear path forward for practical, usable amounts of EV power in flight. Suppose NASA does figure out power beaming: they could just fly a huge jet plane 60 miles up, whose engines would gradually adjust from air ramjet combustion to xe/ion propulsion by using magnets and wires controlling air/propellant flows in the engine (basically like any electronic fuel injection system, but far more sophisticated).
Likewise NASA's nuclear thermal rocket will, eventually, lead to the military thinking they can put a reactor in a plane again. The shift into Small Modular Reactors aids this because Congress wants at least one 100-200 SMR field built, adding ~50 or so onto that order for jet research would be easy. There's precedent for this in the nb-36h.
In other words a LOT of R&D has to occur first just to get NASA and the military using non-combustion tech. Even under the most optimistic timeline, it'd still take at least 20 years for the military to at least plan on having fancy electric-only propulsion in future planes plus another 20 to actually implement it. This might change if better beaming tech comes sooner, but that would also require the government to setup a wireless power grid for airplanes like they have ATC.
