I don't think they will be adding more range, if anything it will be better batteries and some other upgrades but I highly doubt with all the negative attention "Drones" are getting that DJI would fuel the fire with more range. Battery upgrades would make sense as well so that they could sell more batteries since the P3 batteries would not be compatible. This is my Phantom 4 upgrades features prediction list:
Upgraded batteries
Camera compatibility with Osmo (like the Inspire)
1080p Video Downlink Resolution
Faster Max Bitrate of Video Storage
Better Camera Sensor with more megapixels for photos
Maybe, just maybe an onboard parachute or at least options for adding one like dedicated buttons and a spot for mounting on the Phantom.
Greater GPS accuracy
With all the kinks DJI has had to iron out of the Phantom 3 design I don't think there will be major changes to the mechanical or electronic aspect of the quadcopter. I don't think they would mess with the mainboard or motors.