Who knows, maybe there will be no breakthrough in battery design, maybe electric cars will always more expensive than conventional cars because of batteries. Is investing in new technology really cost effective ? Nobody knows, it's a risk, and politically you have to make that risk.

Cost effectiveness is just a measure. You don't ask an accountant to see if a technology is cost-effective, you let engineers design something that do more with less, and do a proper use of levers. Cost-effectiveness will be the mean, not the end.