Hydrogen has a ton of shortcomings still. Technology might improve some of those too, sure. But if 75%, say, of the most severe environmental impacts of cars are mitigated by EVs, leaving a much smaller-sized problem in their wake, the technological advancements will have to be proportionally even stronger and easier to overcome to make the market move on again. (Or if EVs never replace >80% of new gas vehicles or so... but if inertia against change is that strong, that's not a benefit for hydrogen advocates.)
The biggest advantage of hydrogen is that they also solve the most severe environmental consequences of conventional cars, just without creating new ones of their own. It is similar to how LED lightbulbs replaced CFLs, even though CFLs were seen as necessary to replace incandescent bulbs.
80's electric RC cars were slow and the battery ran out in 5 minutes. People who wanted power used ICE RC cars.
Then we got li-ion and LiFePo4 batteries and brushless engines. Now the cars are so fast that regular people need to use limiters when driving. You can get a electric RC car up to 80km/h with off the shelf parts easily.
Short list and no nowhere near exhaustive list:
Extremely high pressures required to get sufficient energy density
Hydrogen embrittlement basically requiring expiration dates on tanks in vehicles
Inefficiency/cost of green methods for producing hydrogen
How to create cheap fueling stations like we have with gas stations
That isn't to say these problems are not solvable but we have been working on them a long time and haven't made a ton of progress. Meanwhile EVs have already been able to overcome most of the big hurdles. I think hydrogen has a possible future in aircraft because the issue of cost, maintenance, and special equipment for fueling is status quo for aircraft already.