Ok, lets NOT talk about a power grid that would be completely overwhelmed and collapse without billions in investment..
I grew up in the mid west, where winter temperatures frequently spend weeks in the below zero range - battery efficiency simply doesn't work well enough there... so cross off 1/3 of the country..
Now I live in the PNW (pacific northwest, for you non-tree huggers) , I commute about 15 miles to work, and yes and EV would suit my commute need - BUT, I pull a camper for vacations and hunting, so my usual driver is a Ford F350 diesel... I have no room to park another vehicle. So either I give up all my hobbies, or 'they' build a 4x4 EV with a 300 mile range while pulling a 30' travel trailer. (Actually, I usually drive a motorcycle to work, unless it's raining - remember, the PNW thing, so that happens alot)
In full disclosure, my wife drives a Prius. Her commutes are anywhere from 2-4 hours, depending on destination. (she's a corporate officer for a company with many locations) The 50 MPG is good enough, and we don't have to worry about a charge problem or availability when she's a couple hours away.
So between the Plains/Midwest temperatures, lack of infrastructure across the entire US, or lifestyle - I'm would be willing to bet the actual number of people who COULD switch on a practical basis to an EV is fractional of their WAG number.