Re: "GM is projecting an all-electric future..."
EV chargers should have multiple charging cables coming off of them, and enoguh power to run one at a time at the maximum current.
You say that as if you'd have some kind of charging octopus with cars all around it. Bit of a bugger to situate that at service stations and other charging locations in a way that all spots are still easily accessible.
Much simpler in my view to arrange the chargers like petrol pumps are now, and link them electronically.