Out of curiosity, I went back to see what unannounced games were revealed at Microsoft's E3 conference last year. Halo 4 was announced the previous year, Tomb Raider was announced on December 6th, 2010. Black Ops 2 was announced the April before E3, Forza Horizon the March before it. Fable: The Journey was alongside Kinect's release, and similarly, RE6, South Park, and Madden were all shown months before the conference. Which leaves Kinect Training, four XBLA games (of which only Wreckateer has ever been seen again), Dance Central 3, and Splinter Cell Blacklist as new game footage.
But you're right, I am sure Nintendo is cancelling because there are no new game reveals for either of their systems.