That’s an interesting idea! Would Gary want to record one for posterity and to preserve his side of the story? With itty bitty digital recorders you wouldn’t even need a studio for such an endeavor.
The thing is it wouldn’t have to be a bitchy anti-Lucas thing (nor would we want it to be). I just think Gary would do a great commentary given how involved he was with every aspect of the film’s creation. He clearly understood the mythology and was deeply immersed in the nuts and bolts of the entire production. The bonus would be the fact that, unlike George, Gary actually likes the films as they were!