That really does not seem like something Apple would do. Way too obscure with very little practical use for 90% of people buying them.
I think if it gets reliable enough, the audio thing would. Four guys with instruments standing in a circle. Place the iPad in the middle and record a 4 track audio recording.
As for the cameras, honestly I see potential for gaming purposes. Make a multiplayer map online that matches your backyard in seconds? hell yeah.