ps. Canon could take some inspiration from Nikon when it comes to battery grips.
Agreed - Canon could force you to buy a grip to unlock a higher frame rate for the camera. That would be lovely.
Right - as a previous user mentioned, they could require the grip to unlock certain features. They could halve the frame rate without the grip, or maybe they could cripple bracketing - oh, I know! Maybe they could eliminate some of the setting views from the two integrated displays, and move those displays into the grip, or perhaps they could eliminate the realtime clock and move it into the grip, so your photos aren't timestamped without the optional grip. I like your thinking; they could take a cue from Nikon and expand upon their business model, and create a whole new revenue stream.
I said "inspiration" not "directly copy Nikon's grips"
I mean simply how the grip attaches - that arm sticking up into the body isn't the best solution in the world. Canon already have the wireless file transmitter grips - they could easily apply that design to a dedicated battery grip.
ps. going a little overboard on my mention of Nikon there - chill out guys, chill. out.