The Hydrogen Engine will help replace Petrol and Diesel Engines whilst co-existing with Electric Vehicles (EV). There is not enough material or power sources to go all-out electric, therefore Hydrogen is the next best choice. Car manufacturing companies would be making a big mistake solely producing electric vehicles.
One good reason to use Hydrogen is because the Hydrogen Engine is not dissimilar to the manufacturing process of Petrol and Diesel engines. The transfer to Hydrogen would be cost-effective regarding infrastructure already in place.
It is clean, and fuel is ever present. To combat lag, Turbo's should always be implemented in engine design. Obviously there is an issue with the storage of Hydrogen, however, solutions are available. One method would be to use Carbon Fibre doped with Graphene.
The Hydrogen Engine will be fully implemented.