Damn. You're right, why AREN'T we talking about this more??? I've held off on purchasing a mirrorless DSLR because either the 4K capability was lacking or it was micro-four-thirds sensor. Finally, the answer!
This article goes into more depth on the video features. Just amazing it took this long to get those features and it wasn't Nikon or Canon.
Producer/DPDenver Video Production
I always say I'd rather see so footage with great lighting shot on a VHS camcorder that something with crappy lighting shot on a RED Helium or whatever the most expensive RED is these days. When I first started out, "building my reel", I spent my money on lights first. Lights don't go out of style like cameras do. 13 years later, I still use those same lights I bought back then (and they are now part of my inventory for my Denver video production company) .
But back then shooting video on a DSLR hadn't been invented yet, which is to say, cameras that could shoot quality footage were still expensive relative to today. So if it building your reel out that is the main goal, then I suggest, after lighting gear, getting a an older HD camera on eBay for cheap (your reel is going on the internet, and nearly all computer screens are still HD). If a 4K gig comes along, tell the client, "yes, I have a 4K camera," then go out and rent it.
Right now my jobs are about 60/40 4K vs HD. A year ago it was 40/60. I shoot for Nat Geo, Discovery, Showtime docs, and feature docs and yes those are all 4K requests now. The stuff that is still HD is usually corporate and not something that is going to have a long shelf life or is just going to the web. For the broadcast stuff, often they will have a specific 4K camera request (last year I shot everything from Amira, Alexa, Alexa Mini, FS7, and Canon C300 II), so like a poster noted above, you can drive yourself crazy trying to nail the most-asked for camera. It used to be easier with only a few players in the game (Panasonic, Sony, Canon) but as manufactures proliferate it is getting harder and harder to guess what is going to be the go-to camera across the industry. The last one was the Canon C300 M I. Right now it might be the Sony Fs7, but nothing near as consistent in terms of requests as the C300 once was.