I think that Hydrogen and ethanol are both dead ends. Hydrogen would require too much infrastructure, and it's not an energy source in and of itself so it combines the worst parts of gasoline with the worst parts of grid power. Ethanol is barely energy positive, and we shouldn't be cutting into our food crops anyway.

I think that, at least in the near term, hybrids and plug-ins are the way of the future. It won't take a whole lot of advances in battery technology to make pure plug-ins practical. They can get 100 miles out of them now, up that to 300 miles and you've got a gasoline replacement without the need to upgrade infrastructure.