I think if the politicians stopped focussing on battery powered vehicles for a moment and started planning for hydrogen the manufacturers would quickly switch resources and research into fuel cells. It seems to me that practical fuel cell cars are already available and it just needs serious input into infrastructure and mass production to reduce costs. As time passes the next generation will be even lighter and more efficient.
The trouble with that notion is that we don't have any socialist governments in the west. You are proposing a level of centralised planning of the economy that simply doesn't exist. The government sets emission limits, it's up to the manufacturers to decide how to meet them.
