You act like there's no research papers on this subject. There have been tons, and the conclusions in each case are the same:
1) CO2 emissions would decline even on the US's current grid (which is, I should add, getting cleaner every year, while the amount of emissions associated with oil production keep rising)
2) On a generation basis, every region in the US has enough space capacity for a full switchover of the passenger fleet today, without any new plant construction, except the Pacific Northwest. Most charging is done at night when most power plants lie idle, but the Pacific Northwest is an exception because their heavy use of hydro means time of use isn't important, only net consumption.
3) The only thing that there's not enough of at present is simply local distribution capacity, to peoples' homes.
Of course, that's for a complete, instantaneous switchover, which is of course an impossiblity. Your average car is driven for about two decades before it goes to scrap, only a small fraction rotate out of service every year. And that's assuming that everyone bought EVs as replacement, which if course is an impossiblity because even if everyone was suddenly sold on the concept of EVs it'd take a decade or more to ramp up production to that level. And of course everyone is not suddenly sold on the concept of EVs. You're looking at maybe a 30-40 year transition time period here. If power companies can't keep up with a trend that's stretched out over the scale of several decades, they deserve to fail.