Xbox ONE hdmi passthrough

I am really excited to see whats possible with the xbox one's new digital hole of wonder. I curently use an apple tv with apps tied to our cable account for family entertainment. I plan on using the apple tv with hdmi passthrough just to keep from switching back and forth. But now, I'm thinking of what would happen if I plug my xbox 360 into the port. Will I be able to play 360 games but take advantage of any X1 features or processing power? I wonder if I can play GTAV using the new controller? Will the universe explode if both the old and new kinect are being used at the same time....

What happens if I use an HDMI switcher and plug all my device into the port?

Please share any creative ideas for making this truly the "one" system to use.