I do hope that suddenly in 2030, something in the hydrogen invested countries like Japan happens where they suddenly flood the market with step changing tech that will complement exisiting LFP/ Sodium ion and other tech especially for longer duration storage (weekly to monthly may be not seasonal but still useful).

It feels like they are working slowly and steadily on the tech and have been doing it since many decades although they never planned to scale it like China did with batteries or solar for numerous reasons beyond the tech folk's capacity

It would be great but it seems very unlikely to me. Hydrogen is difficult to store; it's corrosive and leaks out of the tiniest holes. (Like, the ones between molecules.) It requires high pressure to get a reasonable quantity, exacerbating those problems, and very dangerous if pierced.

It just doesn't seem reasonable. If we actually had a lot of hydrogen gas around, it would be far easier to distribute and use in the form of hydrocarbons, which would allow us to use existing technology rather than invent new ones.

I'd love to be wrong about this, and clearly there are scientists in the domain who disagree. But it just doesn't seem reasonable, and it has a whiff of being used as a deliberate distraction to slow investment in renewables that can be deployed right this instant.

I have to opposite feeling: as the fossil fuel money for "grey" hydrogen dries up and the batteries get better, we'll gradually stop hearing about hydrogen.

Hydrogen production by electrolysis is relatively efficient, with 80% efficiency regularly achieved by modern electrolyzers. It's the reverse reaction that causes problems; 60% is very good for a fuel cell.

So you can avoid the issue if you can use hydrogen to do useful work directly. The simplest cases are iron reduction from ore and heating via absorption heat pumps. Iron reduction works pretty well, but absorption heat pumps have limited exergy efficiency (a measure of useful energy available in heat) when using a very high temperature source like a hydrogen flame. An alternative is to use the waste heat from a fuel cell to drive an absorption heat pump, effectively converting hydrogen to both heat and electricity, the latter possibly being returned to the grid or a battery. But this creates a complex system of energy distribution, which requires some fancy load balancing on the electrical side. District heating allows you to avoid having a fancy fuel cell in every residence, but it requires infrastructure.