Since pure battery electrics will always have lower operating costs (if the hydrogen is produced from electricity and not oil/gas), and that a BEV is cheaper to assemble (less parts, less piping), the market for hydrogen cars is completely dependent on the price of batteries.
As batteries get cheaper, and rapid chargers get faster, the niche that hydrogen can occupy gets smaller.
The thing is, hydrogen cars are electric cars. It's possible some of them will even include a larger battery and become plug-in. So every hydrogen car sold will also benefit the development of better BEVs.
To me, this is a clear feedback loop that benefits pure BEVs. And where will BEVs be when hydrogen cars actually hit the market with significant numbers and models? What if 150kWh batteries are standard? What if 400kW charging is standard? What if the price is not much higher? These are all within reach. It's just a matter of time, and the hydrogen economy does not seem to be moving fast enough that its got time to spare.
But I fully support all subsidies and financial support for development of hydrogen fuel cells. Maybe it won't be success in cars, but it could be in other fields.