Keep in mind that cameras like this are often more the sum of their spec sheets. As compared to the a9ii, it's a heck of an upgrade for sure and it's probably close to the a1. Keep in mind the maximum frame rate for the a9ii is 20FPS and you have to go to 12 bit lossy compressed to pull it off. The R3 can do 30 lossless at 14 bit (according to Jeff Cable, a friend of mine who was testing it at the olympics). That in and of itself significant. Even the a1 can't do 30FPS with dropping to 12 bit lossy RAW.
In addition, we don't know how good the AF is. I can tell you that the R5 is incredibly close to the a1 for wildlife work. This camera will likely have better AF performance than the R5, so I predict it'll edge out the a1.
I do wish it had identical memory card slots, for this level of camera two different types is not ideal - but @ $400 for a 160 CFa card, at least the CFb cards for this camera won't set you back as much.

. Also, if you like having a grip, it does add $400 to the Sony cameras as well.
Also, 24MP isn't bad at all IMO. I shot the D5/6 for years and the D4 before that. Low MP is fine if you know how to use it (i.e. learn how to get close. don't crop, etc). I have hundreds of thousands of images at 20MP and have never had an editor balk at the resolution (although, admittedly, I don't do concentrate much on editorial work anymore) and have fearlessly made large prints as well.
The EVF is a bit less than expected. I had hoped for higher res and frame rate, but I suppose we'll have to see. The a1 EVF is so good I forget I'm looking at an EVF!
Still, overall, I think this one is a winner. I think $5500 is probably a better price, but I still think the R3 is going to impress. I may just go pre-order one