The 400,000 mark is, Sales of plug-in electric vehicles may miss ambitious estimates - SiliconValley.com IMO, numbers turn on cost of fossil fuel, versus poor economy. Even if gas hits $10/gallon folks won't buy plugin's if they can't afford to pay the rent.
That had some things quite out of context » Electric Vehicle Geographic Forecasts Pike Research Note that is a year, not cumulatively. » Nearly 1 in 4 Plug-In Electric Vehicles Sold in the United States From 2012 to 2020 Will be Sold in California Pike Research Pike hits Obama's goal of 1 Million plug-ins in 2018, instead of 2015, and frankly when the goal was stated, few believed it. The cafe standards should encourage a big range of models in 2016, leading to this 400K/year sales level in 2020. Note that is pike not me. IMHO we will hit the 1M in 2017.
400k a year by 2020? thats not small numbers... some drastic change in cosumer thinking will be needed and some major price cuts.
what is difficult to project is advances in technology. and the more plug in's sold, the faster tech will advance.