DeMarcus Davis

Of ALL the photogs I share the field with, I have only seen TWO (firsthand) use mirrorless cameras for NFL in-game shooting. One as I previously mentioned) used a Sony ( and sinced switched to a Canon system out of frustration) and another used what looked like a battery gripped Fujifilm X-T2. Mirrorless MAY become more mainstream in outdoor sporting events, but that is a more wait-and-see than an eventuality. 
Simply put, pro DSLR camera auto focus tracking is superior to ANYTHING a mirrorless body has put out at this point. It's just a hard fact. I REALLY LIKE my Nikon Z6. It's GREAT for portraiture, landscape, travel photography and is mobile and light (with it's native lenses.) However, I cannot endorse or promote ANY mirrorless for NFL/fast action sports.

I watched that video and he has some valid concerns and solid praising. Having said that, he is both right and wrong. He's correct in that to get the very best out of this camera, you need to utilize an external monitor to unleash the 10-bit 422 Apple ProRes. Then again, he's a cinematographer and for that line of work, he NEEDS that 10-bit 422 color space for proper color grading. However, he's also wrong, as for the average user, vlogger, or youtube content creator; an 8-bit standard color profile straight out of body image is MORE than enough. Especially for those who need to crank out videos fast.
Odds are, if one is a serious hybrid shooter, you likely already own an external monitor. If for nothing else, my eyes strain looking at the back panel LCD. Using a 5" or larger monitor makes it easier on the eyes and allows for MORE video tools; better focus peaking, better zebras, better waveforms, and offers scopes, 1:1 and 2:1 zooming tools (while recording), offer multiple aspect ratio framing, viewing MULTIPLE audio channels simultaneously, and allows you to add external audio and ultimately bypass the camera's preamps (which often can be far less than clean.)

I watched that video and he has some valid concerns and solid praising. Having said that, he is both right and wrong. He's correct in that to get the very best out of this camera, you need to utilize an external monitor to unleash the 10-bit 422 Apple ProRes. Then again, he's a cinematographer and for that line of work, he NEEDS that 10-bit 422 color space for proper color grading. However, he's also wrong, as for the average user, vlogger, or youtube content creator; an 8-bit standard color profile straight out of body image is MORE than enough. Especially for those who need to crank out videos fast.
Odds are, if one is a serious hybrid shooter, you likely already own an external monitor. If for nothing else, my eyes strain looking at the back panel LCD. Using a 5" or larger monitor makes it easier on the eyes and allows for MORE video tools; better focus peaking, better zebras, better waveforms, and offers scopes, 1:1 and 2:1 zooming tools (while recording), offer multiple aspect ratio framing, viewing MULTIPLE audio channels simultaneously, and allows you to add external audio and ultimately bypass the camera's preamps (which often can be far less than clean.)

I watched that video and he has some valid concerns and solid praising. Having said that, he is both right and wrong. He's correct in that to get the very best out of this camera, you need to utilize an external monitor to unleash the 10-bit 422 Apple ProRes. Then again, he's a cinematographer and for that line of work, he NEEDS that 10-bit 422 color space for proper color grading. However, he's also wrong, as for the average user, vlogger, or youtube content creator; an 8-bit standard color profile straight out of body image is MORE than enough. Especially for those who need to crank out videos fast.
Odds are, if one is a serious hybrid shooter, you likely already own an external monitor. If for nothing else, my eyes strain looking at the back panel LCD. Using a 5" or larger monitor makes it easier on the eyes and allows for MORE video tools; better focus peaking, better zebras, better waveforms, and offers scopes, 1:1 and 2:1 zooming tools (while recording), offer multiple aspect ratio framing, viewing MULTIPLE audio channels simultaneously, and allows you to add external audio and ultimately bypass the camera's preamps (which often can be far less than clean.)

Just use one of the Kipon Baveyes MF-to-FF focal reducers made for the Nikon Z-mount.  As an added benefit over straight MF, you get an extra stop of brightness.

The Fuji will eat the GH5 for breakfast in stills. Not to say that you can't get decent stills out of the GH5 but it's not its biggest strength. 
For video I still have to give the heads up to the GH5 though, especially for event shooting. Fuji is getting really close though. I think I'm the most excited to see where they're going out of every other company, though I'm very interested to see what Panasonic has in store with the GH6. Fuji though is in the same advantageous position that Nikon is in where they don't have to worry about protecting a cinema line, so they're pretty much free to do whatever they can. 

I dunno if buying a secondhand 7-year-old FS700 + used shogun is really worth it... just to get 4K 10 bit 422.. in 2019..
At that point might as well get a Z6 + Ninja V and get access to 4K 10bit + ProRes Raw.. and enjoy a compact FF camera with IBIS, strong AF etc..

Not at all true!
Just add on the Atomos Shogun, which is always going to be cheaper to buy secondhand than the FS700 itself is. 
What is complicated about it? Nothing. 

It needs no more add ons than an a7S / a6500 / GH5 / etc would need at a minimum (i.e. just the normal stuff all cameras needs: media, lenses, and power). 

To be honest, I am holding fire on a decision until I see the new firmware. Sony have stepped up their AF on the A6400/A9 and I am guessing there will be a video oriented release taking on the z6 (A7SIII, A7IV?) which will have to be competitively priced. Can Nikon improve their already good AF to keep up with a firmware update? Particularly in the field of action stills, the Z6 is not really a sports camera, the DSLRs still have the edge for stills. The ideal hybrid video/stills action solution is still not there; the A9 is perhaps the closest, but still expensive and lacking key video features like profiles.
 

Yes, Nikon is one of the top choices for video (arguably the #1 choice), yet their perception is not even "mid back" but "last" (ignored alongside with Pentax etc). 

Nikon has a serious marketing problem, and giving us raw video from a $2K full frame mirrorless exactly what they need to do to make heads turn and finally pay attention.