The (rumor) is false. And that rumor centers on the D850. The truth is the D850 makes all lenses used on it BETTER.
And the fact is this, Tamron lenses are designed to work on several camera's, Nikon lenses, on the other hand, are specifically designed to work on ONLY Nikon camera's. I could go into a very long discussion about third party glass, but I will not.
Let me just say that the Nikon 70-200 VRII and it's successor do a fine job and deliver outstanding results time and time again.

GROUP AUTO FOCUS is all I use and my keep rate is almost 99%. I assign the rear focus button to single spot focus for when my subjects are in the branches and I want to make sure the branches do not effect the focus point.
GROUP AUTO FOCUS is outstanding for keeping the eyes in focus, as long as one of the four focus squares that show in the middle of the viewfinder is on the bird, it will be in focus. Group auto focus was designed to ignore the back ground and keep focus on your subject. Keeping all four spots on the subject is even better. Good luck and keep on shooting until the end.
Shown below, Green Heron, Wakodahatchee Wetlands. Grab shoot using Group Auto Focus

Nikon recently added a firmware eye focus system to the Z's ONLY.
I believe the next generation of D500, D850, and D5 will all have eye focus capabilities. I believe they are currently experimenting with the Z's to see how it goes. They must keep pace with Sony. Right now, the Sony system is in graduate school and everyone else is in elementary school when it comes to eye focus systems.
So, to answer your question, in a year or so the D560, D860, and D5s or D6 will have it. Stay tuned.

Coworker. Do you plan to go professional? If yes, the going rate is 3 times your cost minimum. No, hourly charges are for pre assigned work, not after the fact.
Cover your costs and add enough to buy you a drink after work. It's a cell phone photo after all.

SONY. the one and only

Looks like your considering three camera's. There are many sites on google that compares them. Here is one
https://www.bhphotovideo.com/c/compare/Nikon_D750_vs_Nikon_D500_vs_Nikon_D7500_vs_Nikon_D7200/BHitems/1082604-REG_1214162-REG_1333060-REG_1127272-REG/?c3api=0980%2C%7Bcreative%7D&m=Y&msclkid=cfb5f28da6311cd763f4afa40f250ac4

There are many, many, more. If your into sports, the D7500 and D500 both have a focusing system called GROUP AUTO FOCUS, which, is out standing. BUT, the D500 has a separate focusing engine, the same focusing system that went into the D850 and D5.
So, for wildlife and sports, if that is your game, go with the D500. For general shooting, either the D7200 or D7500 will do. By the way, many here will harp on the fact that the D7500 only has one memory slot. But, for the past 15 years of digital, I never needed more than one slot.
All three will deliver, it is up to you to match the camera to your current and future shooting needs.

You can add digital images to a power point presentation. Just the photo's will show. NO problem. And, you can always add words too. Power point is still a great way to make a presentation, and just put it on a memory stick and take it any where.

I called Nikon yesterday. NO PLANS FOR D860 or D760. Rumors are always going to be there. Yes, eventually their will be a successor to all camera's. But only the company knows, and they are saying NOTHING. And NO ONE else knows either.

So, basically your trashing early Sigma camera's. One of the reason's their lenses were OK is because some or their early camera lenses were made by Nikon.

I will agree to kindly disagree. My folks tell me a different story. Maybe they are the only ones reaching their sales goals, maybe many others are not. How knows. All I know is the guys I talk to tell me they are reaching their sales goals.

Believe what you want, and I will believe what I know. Thanks for the comeback.

No thanks. I have faith in friendship. No misleading SEC fake news.

I respectively disagree. So do my two photographer professors at Ohio University.

Understand your position.
Nikon is releasing firmware to improve the focusing on their Z series camera's (which was a big knock on them). The firmware reportably makes the Z camera's capable of focusing on the eyes of people. Later this summer Nikon has mentioned that they will release more firmware to make their Z camera's focus on the eyes of animals.
IF this happens it could be a game changer for the Z camera's. I have always liked the two major advantages of mirrorless camera's. They are: 1. No need to ever fine tune a lens ever. 2. in Manual you see exactly what the exposure is going to be before you take the shot.

My sources? As a old fart Nikon Rep. from before time I keep in touch with my colleagues still in the business. Some of my old friends have gone over to the dark Canon side. They all report sales are up and have had a sustained 10 year growth. Since they are in the business I tend to believe them. They also tell me that they have all met their sales goals and get their annual bonus checks on time.
Now, I guess you could say they are all lying and sales are not up and they are not meeting their sales goals and are not getting their bonus checks, if you want to.