GM doesn't need to answer to this. If people want a GM performance vehicle they have plenty to choose from already:
Camaro Z/28 (soon)
Corvette Stingray (soon)
Chevrolet SS sedan
GM builds trucks for what they're supposed to be used for. And we all know GM can do it if they wanted to. Remember the Cyclone or the Typhoon?
GM has so many toys in their toy chest Ford HAS to do stuff like this. What else do they have? The Mustang. That's it.