Keith over at Northlight Images has uncovered a Canon USA patent showing what appears to be a “universal” battery grip for Canon cameras.
It looks like the battery grip itself can use various “adapters” to fit on various camera bodies. There is also gearing that allows you to move the position of the tripod screw.
You can see in the images below two different camera bodies illustrated and how the adapter could work between the camera and the battery grip.
I think this would definitely be a welcomed advance in battery grip design for consumers.