Yeah, hydrogen is something that only starts to make sense as a motor fuel at the point when we already have very abundant clean energy from some other source- likely nuclear or something along those lines. Otherwise, it’s almost always cleaner to just use the fuel directly if it’s natural gas or petroleum.
As best I can tell, the reason hydrogen (or any gas really) works well in Wankel engines is because metering it into an air-fuel mixture is easier, it burns faster, and emissions aren’t so much of an issue with hydrogen. All of those things are issues with using gasoline in Wankel engines, and hydrogen obviates them all.
But that doesn’t mean that it’s necessarily any sort of wonder technology; AFAIK natural gas would work the same way as hydrogen in a Wankel engine, and we don’t see a lot of Wankel-powered natural gas generators, cars, etc… even though natural gas fuel is commonly used in things like municipal buses and stationary generators.
Maybe if we start shifting to hydrogen as an energy carrier (i.e. carrying energy from some other process like nuclear or solar), then Wankel engines might make some kind of sense, but I’m inclined to think that if they’re not already getting serious use or scrutiny in the existing gas fuel applications, it’s unlikely to happen just because hydrogen becomes popular.