The Pro Drone looks interesting and has a nice mix of Phantom/Inspire features but the big difference I see is the 2K limit and how will video transmit that far compared to Lightbridge? Of course we won't know until it is out and compared but that video stream is DJI's strong point.
Now what I think 2016 is going to bring is some turmoil, maturation and settling of the hobby/pro UAV world.
Also, the ability to pass from pilot to pilot is going to be a big pro feature we will see more. It allows operation to be relayed and thus a longer single flight pattern.
P4 ? - Retractable landing gear, removable camera that goes to an Ozmo 2, longer flight times on the Pro and Adv versions, an emergency chute, a water resistant/floating option for major $$$ . Just my guesses.