The saudi oil minister said that if everyone in the world had as many cars as the US, then they wouldn't have enough oil. So that's a very aggressive yardstick you're setting for EVs.
It would be much more sensible to electrify the cars/busses/trucks/delivery vans that are driven a lot, that are driven in stop-start traffic, and that are driven in heavily populated areas first. That gives you much more bang-per-buck in terms of pollution and CO2 reductions.
There are a lot of things which fail to scale to an Earth-of-Americas. And some pretty good reasons to think that's generally not possible.
Pointing out which specific subcases remain impossible doesn't disprove the larger case.
There's a good question as to how scalable EV's are generally. Present scale is minuscule. A small feaction of a percent in the US, and that actually fell in 2015. I'm not sure what 2016 and future trends (based on pre-orders) look like.
I'm really looking forward seeing big cities adopting EV for buses and cabs. In London the black cabs are noticeably more smelly than regular cars, and buses are... well buses.
It would be much more sensible to electrify the cars/busses/trucks/delivery vans that are driven a lot, that are driven in stop-start traffic, and that are driven in heavily populated areas first. That gives you much more bang-per-buck in terms of pollution and CO2 reductions.