First off the context I'm coming from is as a fashion, and commercial photographer who shoots with Nikon. I've been playing with Fujis for the last couple of years, and been following developments very closely, but haven't invested yet. I'd also like to add that I'm looking for camera systems that have strong options for photo and video. I'm not interested in buying a dedicated video camera as I'd just rent out a RED or similar when budget allows.
Anyone who works in the commercial photography scene will know that video is creeping in to the field quite fast. It's becoming a necessity to expand your skill base, and photographers are expected to direct video, and stills on one day.
Now after a long history of a single-minded focus on stills (which I fully appreciate), with the X T2 Fuji has proven that it can develop a camera with strong video capabilities. 4k from oversampled footage, and F-LOG. This is important because as photographer have to take on extra responsibilities, so does their gear.
Currently Nikon video game is lacking. Sony has the A7r range for photos and the A7s range for video. Micro 4/3 has Olympus for photos, and Panasonic for video. Canon has DSLRs for photos, and a whole other video department (their DSLRs are about equal for video as Nikon)
Part of the reason Sony, and Panasonic are doing so well for video is Price, and Weight. If you're using a Gimbal, or a lot of other equipment, weight becomes very important.
I'm currently not interested in investing in Sony as it provides no benifits over Nikon in my opinion. I've shot with top end Olympus before and I'm not really a fan.
This is what Fuji would need to create a very strong mirrorless that could compliment their photo based lineup, and strongly compete with other video centric cameras.
HDMI out, while recording to SD card (for external monitor)
In camera features like focus peaking, LUTs, etc
Fully articulating screen
Good sound input & Headphone port
A zoom lens with great continuous video autofocus (maybe this is for firmware or in camera autofocus)
4k, 60fps (2k 60fps would be fine)
High bit rate recording
A phone app that can be used as external monitor with controls, focus peaking, LUTs, etc would be amazing. (this saving costs of external monitor would be instant buy for me)