Well, it's as big a leap as the extension of the monorail. (Sorry I had to bring it up again) The gap between experimental trial runs and reality is decades in the future. First the cost has to go down, because no matter what lip service people give the green environment, it's the green in there wallets that actually push the realities. Second it's the reliable power source. Environmentalist do not want coal, oil or wood fired generation because of air pollution. Wind power is out of the question...it is sight pollution. Water power is detrimental to fish and other aquatic creatures and Nuclear power will fry us all and, at the very least, make us sterile. Which when I think about it would solve all the problems. No people, no problem!
Funny, when I was a high school student in the mid 60's that thought was already on the table. It was not just cars though it was also your house would have a fuel cell that ran everything independently of any outside need. Bet you can guess what or who put the cabash to that little research project. Oil and electric companies would be the correct answer.