That would be very cool if it turned out to be the case.
The current Xbox controllers are USB as well, but they have one extra wire (yellow), and its only reason for being there is for lightgun use.
That being said...
We may never actually see a lightgun on 360.
Xbox only had 3 games that used the lightgun, and I don't think any of them sold very well, and one of them was a complete broke pos.
HoTD III