[oneplane]

If the article is anything to go by, the clue isn't as much the fuel cell itself, but the idea of having an engine that can be powered by any source of electricity. So instead of swapping out the engine for a different type, you only swap out the power storage method. If they have lithium and fuel cells now, but something else comes along later, it means a very localised change is all it takes to try it out and if feasible, put it in production.

For ICE propulsion you'd have to change a ton of things if you were to switch fuel types as the engine, the pumps, the tank, the hoses, sensors are all over the place and all have to change when you need to support a different fuel. (i.e. when switching from say, a liquid fuel to a gas or something like that) If I'm not mistaken, that's also why all the changes (not even innovation) have such small impact so far, because all they really can do is make sure that 'new' fuels behave the same way as old fuels, and new engines behave the same on the fame fuel as old engines. It's a deadlock.