The upgrades are somewhat predictable, however I question the actual necessity of some of the features.
4K - OK, great, (I've said this before about the GoPro 4 K stuff) but how many of you have 4K TV's to watch it on or do significant cropping of your videos in post editing? Also will your home computer have enough power to edit these files.
If the camera lens is non-fisheye and a flat horizon, then that is a definite plus.
Streaming live video - another plus
Sensors for flying indoors... I would not fly a Phantom in my house, maybe someday if I have a mansion... or if I get invited to do work at an indoor facility somewhere - not sure how much use this will be. For me, probably none. I would have rather seen a sensor array for general obstacle avoidance.
Web site is back up and they are stating that orders will ship first come first served in late April. Have one in my cart, but I'm waiting to see what DJI will offer me from Customer Service from 2 flyaway situations I've had within 2 months. One was not recovered and the other one was because I had a Trackimo on it and was able to track it down. I won't fly again w/o a GPS tracking device