That's a very tough question.
We know the cost is diminishing—the cost of production, the cost of hydrogen, and so on. Nobody knows exactly when. Consultants claim it will be by 2030, but we'll have to wait and see.
If I may add, there was a survey in 1975 claiming that 10% of cars in the streets would be electric vehicles. That was a long time ago, and it was completely wrong. It's always difficult to make forecasts on energy for the future.