Agreed.
A more appropriate metaphor might be a film camera company making the transition to digital. Nikon and Canon did just fine. Minolta had some decent digital offerings, then was acquired for its copier business by Konika - and the camera division was sold to Sony - who were producing good sensors, but they needed a 'leg up' in camera design.
Just like Nikon buys sensors, GM can buy battery tech. There's also motor tech and battery/motor management electronics. which they seem to have a handle on.
The rest is understanding how to design and mass produce vehicles that pass NHTSA standards - and the only issue I see there is that the ICE is part of the frontal crash 'protection system'.
GM has a nationwide dealer network. They just need to get most/all of their dealers on the electric bandwagon - they need to not be the 'ugly stepsister' in the dealership - the same way Nikon needed camera shops to take their digital offerings seriously.