That percentage is quite inflated though because they're using the legal definition of "city." Where I live just recently incorporated and is now a "city" but that doesn't mean people aren't still commuting 20+ miles to work in the winter.
That being said, I could easily imagine 40%-50% of people living in dense urban areas either now or in the near future, but there are always going to be a significant portion of people who don't. Given that, the article's premise that the future of transportation is just "personal electric vehicles like e-bikes, scooters, or micro-cars" makes little sense, even if these can replace traditional cars in dense urban settings, there are still going to be a huge number of people who will need a more traditional sized/styled vehicle. That being the case, traditionally sized electric (or other non-fossil fuel) vehicles (such as Teslas) need to be part of the future of transportation if we want to reduce the overall negative impacts we have on the environment.
I would also disagree that there are more "sociological downsides" to living outside of dense urban environments (there are pros and cons to each), but that feels like an entirely separate debate. =]