RE: Tesla's Model S will go 300 miles and cost $77,400
The problem is always the cost of the battery (initial and replacement) and the need for an upgraded costly power grid, capable to provide additional massive power for charging millions of e-vehicles every day.
So the sales of e-vehicles will sky-rocket and totally replace conventional vehicles only when rechargeable batteries will be replaced with another, cheap, powerful, environmentally-friendly, long term power source -like nuclear fusion. Or a fusion-battery if you prefer. There is no future for e-vehicles running on rechargeable batteries.