From theoretical standpoint why not jump ahead to antimatter? :)
Electricity is a solved problem, most obstacles to additional power generation and transport are bureaucratic in nature.
As soon as everyone agrees to build more nuclear power... We're not anywhere near ready to use anti-matter, but the next best thing faces extreme opposition for some reason.
Hydrogen is pretty much a solved problem too. Most of the critics are just stuck in 2010 or earlier.
I did not have primarily nuclear in mind, but obstacles to extending long-distance electric grid to support renewables. But hydrogen pipelines are going to have even worse problem with this. And you did not really debunk any of my "stuck in 2010" criticism.
Hydrogen pipelines are a solved problem. We have been doing it for decades[1]. I could have said "stuck in 1930" but that might be overdoing it.
[1] https://en.wikipedia.org/wiki/Hydrogen_pipeline_transport
And the "special alloys" really just mean certain types of steel alloy, and "nonmetal materials" really mean certain types of plastics. This is not a big challenge.
You still need very low temperatures and exotic materials for superconducting cables. Not to mention the power generation needed to sustain that level of power draw. This is a long-term problem that we're nowhere near solving.
As I said before, this is not a race and there is no finish line. There's nothing stopping fuel cell cars from displacing EVs at an arbitrary point in the future.