Hmmm....
For my needs, I´m in trouble. The 5D4 is mounted on the 600mm Mk II lens, the 500mm was mounted on my 7D MK II. But now in autumn, when deer appears in dusk and dawn, the 7DII shows to much noise. So I was thinking of fetching an Eos R... That would have been an cheaper solution than buying an body >3000€.
For photographing deer, I think that high fps is not such a factor, but for sports like baseball where pros need to capture a specific moment, then use of a high fps might be something I'd want. Most of the time, I find 10 fps just creates a huge editing job when I could have been patient and used one shot. Thats not the case for those with one time opportunities, for those cases, users are still better off with a 1 series.
Canon will come out with a higher model, it will be priced much higher as well, probably $4,000 USD. It will also likely have to be larger, a joy stick, larger battery, more internal room for dual cards, multiple processors, everything adds up where space is involved.
Adorama, here in the US has a optional membership club that gives 2 day shipping for orders, 60 day returns, etc. A person would have a reasonable time to evaluate the camera and return it if it just did not work out. I am occasionally disappointed with a product that does not work for my needs, and I do return it if that's the case.
You might look for a used 1DX to upgrade the 7D II, or a 2nd new or used 5D MK IV. There tend to be good deals coming in the fall, so decide what you want and be ready to buy.
My 5D MK IV seems to me to produce too much noise, I don't think it is any worse than my MK III was, but perhaps a different texture of noise. Obviously, a APS-C sensor is going to have even more noise, its definitely a issue in low light.
