Thanks for keeping this topic alive...I love to speculate/theorize.
Okay...as far as using gyro motion control (wether one handed or two handed) I see only some games using this some of the time. I don't expect all games on Revolution to use it nor use it all the time...that would cause problems with not only arm fatigue, but imagine multiplayer games requiring multiple people to flail thier arms causing bodily harm and needing too much space just to play a game. No...I don't think the interface will be that demanding/limiting to the player. I imagine that some games would only require it slightly (steering, piloting, tilting, simple hand motion (not neccessarilly your whole arm), jerking, etc.).
As far as using a dual-weilding control method...again, no...I don't imagine all games will use this either. However, the prospect of such freedom and immersion really brings out the potential in gyro motion control...it puts it above merely a tilt pack. Imagine shaddow boxing in PunchOut!, hang-gliding in Pilotwings, virtual lightguns in both hands or even sword & shield control. Not saying all games should forever use this or be limited only to this...but I think gamers and non-gamers would be curious about such ways to play.
Practicality and doability beyond that is there...it's just designing a controller that is accomedating for that type of gaming (as well as more traditional gaming) is needed. That's what I'm trying to visualize. In the concept I've already posted (the two peice interface), I agree that there's issues with how such seperated grips could work plausibly, let alone price/battery life issues. Hence, why I posted again about a one-peice design I'm now working on. However, with the one-peice design I'm working on now, some games could still use dual-weilding by holding a controller vertically in each hand.