6 Months ago everyone was covering Nikon with dirt, now they are the greatest since sliced bread. It is fine and dandy to get cheaper gear, but if camera companies don't make enough profit to make it worth while they will throw in the towel. Be careful in hoping for a race to the bottom.
If is nice to have three major players in the market. Keeps prices in check and innovation ongoing.
Don't forget Canon has an 800mm lens for less than $1000 since no one cares about f stop anymore.
I know most forum folks dismiss anything but full frame, but I would certainly consider OM System (formerly Olympus) when it comes to wildlife and BIF. So, maybe not a major player in forum members' minds, but certainly a 4th alternative to the "big 3". If you are looking for much cheaper, much smaller, much lighter, I would consider adding a new OM-1 and an Olympus 100-400mm lens if you are looking for 800mm reach for wildlife and birds. People are talking about switching to the Nikon Z9 and this 800mm lens which would cost $12,000, compared to $3,600 for the new OM-1 camera and lens. This Nikon lens - while very impressively priced and small and light - is still twice as heavy as the Olympus 100-400 and over 4 times as expensive. Plus you get the significant advantage (in my opinion) of having a zoom.
Yes, the Olympus 100-400 is not a "PRO" lens, nor a fast lens, so you could choose the Olympus 300mm f/4 (equivament 600mm reach) instead. Adding a 1.4 teleconverter will get you over 800mm and it will still be less than half the price of the Nikon 800mm PF (about $3200 for the lens and 1.4 TC) and about 700 grams lighter. Yes, these MFT alternatives will give you higher equivalent F stops resulting in less bokeh and more noise. For me, the advantages of cost, size and weight far outweigh the disadvantages. Most of my BIF shots are against blue skies or backgrounds considerably far away, that bokeh is not an issue. Noise reduction programs like Topaz and others, make any additional noise (usually rather minor compared to my FF camera) a non-issue.
Plus, Olympus and OM system gives you Pro-Capture, allowing you to catch the action before you actually hit the shutter button. A great feature. If I'm not mistaken, Canon has it in the M6 II (?), but can't understand why it's not in the R5, R6 or R3. (or is it? If it is, please let me and everyone else know.)