As stated in that article, those assertions are from a recent paper entitled “Will We Ever Stop Using Fossil Fuels?”, Thomas Covert and Michael Greenstone of the University of Chicago, and Christopher Knittel of the Massachusetts Institute of Technology.
But I think you read the article too quickly. It says, quote:
"Those estimates may be too conservative, but the high cost of batteries and their short range help explain why EVs still make up only 0.1% of the global car fleet (though getting to 1m of them last year was a milestone). They are still mostly too expensive for all but wealthy clean-energy pioneers. Many experts dismiss the idea that EVs will soon be able seriously to disrupt oil demand. Yet they may be missing something. Battery costs have fallen by 80% since 2008, and though the rate of improvement may be slowing, EV sales last year rose by 70%, to 550,000. They actually fell in America, probably because of low petrol prices, but tripled in China, which became the world’s biggest EV market...Next year Tesla aims to bring out its more affordable Model 3. It hopes that the cost of the batteries mass-produced at its new Gigafactory in Nevada will come down to below $100 per kWh by 2020 (see chart), and that they will offer a range of 215 miles (350km) on a single charge."