Do you think optical flow is going to be a useful feature? I thought it only kicked in quite low. I know the Inspire has it but being a closed system it's hard to tell what it's using it for. I don't fly inside which is what DJI claims it's good for but then again, they also have sonar on it. I think the Pixhawk and Arducopter have supported sonar for some time but I could be wrong. What I'm hanging out for is Lidar as my interest is for the copter to do proper terrain following during mapping missions.
As for the Pixhawk 2, I don't think it could be far away at all. They are already in the Solo copters so it shouldn't be too long. It sounds like it will be quite nice with 3 IMUs, anti-vibration cube for the sensors etc. But the real advancements are happening in the Arducopter software. It just gets better and better with more features and very refined techniques. It amazes me how far they have come in such a relatively short time.