There's one key problem, making hydrogen without creating more carbon in the atmosphere. If they solve that, then it's worth considering. If we have fusion providing endless electric energy (which could be used to split water), then we could just use it to fuel electric cars too. There's the classic problems of lack of energy density, and hydrogen fires not being visible. I think we can probably make hydrogen containment systems better, and figure out how to make fires visible. To me it all comes back to getting the fuel. When we can do that we can consider it.