My primary interests are nature (particularly bird), but I also shoot air shows and quite a lot of radio control model aircraft. I also shoot some landscape and even star-landscape photos.
I currently use a D500, but before that owned a D750.
My feeling is that, for most of your stated interests, the lenses you are planning on buying are too short. This means that you will probably end up cropping quite a lot. And while the D850 is probably equal to a D500 even when cropped to Dx, it is not much superior either once cropped to that level or more, and thus spending the extra money a D850 costs (especially considering that you would really want to add the battery grip and D5 battery in order to get the frame rate up) and struggling with the larger files does feel like a waste. So I agree with the concept of buying the D500.
I would also recommend the 200-500 rather than the 70-200, or even better the new 500 f5.6 pf although considerably more expensive, the faster AF speed will be very useful for air shows. It will make swopping from plane to plane during team aerobatic displays far easier.
As for macro, reversed lenses are to my mind a stopgap, a cheaper alternative to a dedicated macro lens, but if you need to buy a lens anyway, rather buy a dedicated macro lens from the start.
Like Chambeshi, I also love the old 55mm f2.8 AI-S. This can be bought quite cheaply second-hand if you are prepared to search for it, and works brilliantly on the D500. The other macro lens I use is a 180mm f3.5 Sigma. The longer focal length is great for not disturbing the wildlife, and it is stunningly sharp (at least as sharp mid-frame as my Nikkor 500mm f4 VR) and, if you can find one, is also very cheap second-hand. I bought mine for R3500 (about $250)...