Exactly! If we can improve the methods of generating hydrogen, fuel cells have the potential to act as versatile, phenomenally efficient, dirt-cheap batteries, without all the issues of limited metals and dirty production - Being a better battery is a huge deal.
The reason that fuel cells are so expensive is because of limited metals. The best fuel cells are made with a lot of platinum. If fuel cells were cheap and did not need the use of limited metals, then they would be a huge deal. Until then, how you produce the hydrogen is a minor detail. (Maybe there have been amazing advancements in fuel cell tech since I last looked into it. Any links?)
Batteries don't do that great with the limited metals problem either.
The bigger issue for railroads is range; current battery operated trains have a range of about 40km, whereas this hydrogen train has a range of 1000km. You could have charging stations at every station, but then you run into issues if the distance between stations is more than 40km, or if the charging equipment at a station becomes broken.
The problem is that any non-fossil fuel derived hydrogen made from solar/wind loses more than 60% during conversion. Compare that to lithium with around 10% loss that includes outputting the energy (hydrogen would lose even more).
Hydrogen is a terrible battery with very little chance to catch up to current battery tech.