The demand will be there by 2026. I have little doubt of that.
The problem is building the infrastructure. Cars require a lot of heavy industry to build and support. Cars with a new fuel source (electricity in this case) requires a whole fueling infrastructure. Yes people with garages and enough power to their house can charge at home, but about 1/2 the population of the US are renters, and there are a lot of older houses that don't have garages, or even driveways. A friend of mine lives in one of the most trendy neighborhoods in Portland, but everyone parks on the street because the old houses were built before cars were common. On some streets rings to tie up your horse are still there. A whole infrastructure for people who can't charge in their garage has to be built, and a lot of that is going to take buy in from governments, if not the governments doing it themselves.
Then the long distance travel network of fast chargers has to be vastly expanded from where it is today. The PEV market share in the US was 0.72% in 2014 and 0.27% in Canada, and well over half of those were hybrids that don't need charging on the road. Get that even into single digit percentages and you're looking at building a hell of a lot more chargers on highways. It can be done, but it will take time. As long as there is a myriad of charging standards, there needs to be a lot of duplication of effort built in to support all the different charging needs.
Then there comes the problem of building the batteries. The world builds about 100 million cars and light trucks per year, Tesla is aiming to build 500,000 Model 3s a year with the Gigafactory output. To support switching the entire world's car production over to electrics will require at least 200 Gigafactories. The first one isn't finished yet, and while Tesla will probably break ground on Gigafactory 2 in a few years, nobody else in the world is even hinted at being interested in building their own. Most mainstream car makers have their head in the sand about electrics. They build them because they have to and want to appear green, but even the "mass produced" electrics like the Volt and Leaf are built in tiny numbers compared to ICE cars from the same manufacturers. I believe Chevy is aiming to build about 50,000 Bolts a year, less than Teslas production levels when the Bolt will be introduced and one of the lowest volume vehicles in the GM lineup, they sell almost as many Corvettes.
If the Model 3 takes off, the other car makers will panic and get serious about electric cars, but they won't even break ground on the battery factories until 2020 or later. It would be impossible to build 50 million BEVs a year by 2026. If the Model 3 is popular, it's quite possible there will be the demand for 50 million BEVs by 2026, but the market won't be able to deliver. Maybe a few million a year by then. Maybe, it depends on how much resistance there will be from the ICE lobby when the handwriting is on the wall.
Another factor the article doesn't address is young people don't buy new cars anymore. I read something a few months back that the average age of a new car buyer in the US was 50. Some brands had average ages around 60 and I think the youngest average buyer was 46 for something like Range Rover. Only a few 20 somethings buy new cars anymore. The millennials are not as interested in driving as previous generations and many don't get driver's licenses until in their 20s. And when they do go car shopping, they look for used cars. Some of this may be more of a trend in the US than other countries, but the millennials are usually so burdened with debt they are delaying buying new cars, houses, and having families, all of which has a negative impact on the economy.
With consumer electronics, you can see huge market shifts in a very short period of time because that industry is very light on the industrial needs to make the product. You only need about 500mg of raw materials to make an iPhone, but you need several tons to make a car. Consumer electronics also tend to be evolutionary rather than revolutionary. The iPhone is often touted as revolutionary, but none of the hardware was all that revolutionary, it worked with the existing cell network without modifications and basically was just a shrunk down portable computer with a phone function. All the elements were already there to put together. An electric car is a revolutionary thing, it requires a new support network and at least for Tesla, includes some technologies never seen in cars before.
Tesla also has a different approach to manufacturing than anyone else. The Gigafactory is going to be vertically integrated with raw materials in one end and finished battery packs out the other. Nobody in the car business is doing anything remotely like that today. I think it's the wave of the future, but it will take a while for the revolution to take hold and there will be casualties as companies that can't keep up will go out of business.