Since it is only a question of a few weeks maybe a bit more, I guess, before the new Mega is released I'd like to start speculating on what that will be like. Chris and team feel free to chime in as you wish ;)
We know its AtMega 1280 and it will be IMU based. The new AHRS was launched today, congratulations to Jordi on a spectacular achievement, we know you have been working on this dream for a few years :)
It is reasonable to expect that the existing AHRS was developed with the Mega in mind. The sensors was selected at the best price performance point. Will the new Mega use the existing IMU or will it be integrated on the board? I would vote for keeping the IMU as a module, easy then to upgrade the IMU or its sensors, as well as add Magnetometers in future.
From things Chris has dropped here and there, I expect 2 way comms via XBee, waypoint updates on the fly, maybe OSD and full coordinated flight control with ailerons.
Maybe we get PID tuning in flight, a way to trigger camera/video or other payload say from waypoint data or even intervalometer settings to do survey work by calculating the coverage for the camera at height with resolution to give us perfect coverage with overlap ;)
Any other ideas?