Cross-platform games are probably going to have a some form of touchscreen interface anyway thanks to the Wii U, so developers wont have to develop specifically for Smart Glass, they can just port whatever they were doing for Nintendo's console. And, much like Kinect, Microsoft is going to push developers to use the new features even though only a fraction of the players are going to use the feature, particularly for their first party games like Halo.
I can't imagine playing Halo with a touchscreen on a separate device from the controller. Here, let me just put down my controller to pick up my smartphone and change my weapons and -- fuck, I'm dead. Unless the entire game is controlled with the touchscreen, which is all kinds of wrong.