Well, I see no reason not to go with a contoured design. Everyone already knows what iPod touches look like, now just throw on a bigger (4.3" maybe?) screen and better camera + 4G LTE support and you've got your new iPhone. Well, of course a newer processor as well, but that's beside the point. The bigger you make the screen, the thinner everything else can be made because it can be spread out, easily allowing for a contoured design instead of a brick like design. Not that the iPhone 4 is bad in anyway, just its a little thicker than it should be.