I currently shoot with a D850 and have a D800 as my backup camera. I own a lot of Nikon F mount glass...including the Holy Trinity, 105 Macro, 200 Micro, 200 f2, 300 2.8, 500 f4 and Sigma 15 fisheye

So, my migration plan is as follows:

• Just placed an order for the Z7ii.
• Once the Z7ii arrives, I plan to replace the 14-24 and 24-70 lenses with the S 2.8 versions. The S version of the 24-70 looks to be a significant improvement over my 24-70 (first version) and the 14-24 also looks to be improved (although that's tough to do against my 14-24). The filter options for the 14-24 S look to be a lot more convenient.
• I plan to keep my 70-200 F mount (latest version) and use it with the FTZ adapter.
• I plan to keep all of my other F mount lenses and use the FTZ adapter for now.
• I plan to keep my D850 for a while and use it for action photography with my long lenses. I suspect the D850 will outperform the Z7ii for action photography--sports and birds in flight.
• Within the next year, I expect the Z7ii to transition to my backup camera. It's possible that the Z9 (or whatever the model) will be my primary camera, but I'll wait to see the pricing and specs on that first. In any event, once the Z7ii moves to being a backup, I'll sell my D850 and two of my Holy Trinity lenses.
• I plan to keep the long telephoto primes for quite some time and use with the FTZ adapter. I will likely sell one or two of them (probably the 200 f2 and the 300 2.8) in time.

It's an expensive transition, but not as costly as it could be as I'm retaining all but two of my lenses. I have made the decision to stick with Nikon--mostly because I'm so heavily invested in the system, particularly the lenses.

I decided that mirrorless is going to be the future for me and that it's best to start making the transition now. I don't expect the Z7ii to outperform my D850 in terms of image image quality, but I do expect the S lenses to be superior to my F mount lenses...and will also appreciate the size and weight savings. As I'm making this transition, I think I'll be better positioned to take advantage of future advances with mirrorless technology...such as the ones we are already seeing with the most recent Sony flagship body.

So, that's the plan. I made the first step by placing an order for the Z7ii today!