So, I'm pretty sure we'll see the EOS R II announced at the same time as the 5D Mark V, and both will have the same sensor. Probably no more than 32-34mpx, but unlike the current generation I predict it will have:
2x UHS II slots (no CF express)
Probably no IBIS
A better focus adjust joystick or similar.
Faster frame rate than the EOS R
Larger raw buffer.
Probably faster DIGIC = faster/more accurate Eye AF.
Full-width 4K video done reasonably well.
Better intelligent auto scene and intelligent focusing. I know a large part of what Canon's Ambassador photographers do is to generate a huge amount of images with metadata that Canon use to crunch for their AI to better understand how and where to focus and the other settings required for generating decent shots in 'full auto' mode. I know it's probably heresy here to say so, but Canon are working on a future where the camera is likely better able to make the right decisions about camera settings and focus points than the photographer in many cases. A lot of the improvements we are likely to see in the EOS R line in the future are to do with software and AI. You'll still be able to set manual mode if you really want to, boomer
[Note: Pure speculation ahead!]
I don't actually think the EOS R was ever meant to be a production camera for sale. I think it was a hacked together design meant for limited production for testing, for getting the RF lenses out in the field. I think the EOS RP was actually planned to be the first RF mount camera out for the public with the EOS R coming later (and somewhat like the EOS R II specs above) , and I think that two things happened. Firstly the feedback from photographers especially with the 28-70 and 50 lenses told them that a more serious body was essential for launch (I doubt those two lenses would have launched with the RP, they would have come later. We'd have had the 35, the 24-105 and perhaps another design that never made it passed testing). But more importantly, they found out about Nikon's timing for the Z system and decided they had to rush something out before that. This explains why the body doesn't really seem complete. The touchbar is an experiment that didn't really work, the single card slot was obviously going to cause issues, and the use of a dated sensor incapable of full-width 4K was problematic.
It also explains how it was rushed out with essentially beta firmware with features such as Eye AF not finished.
The EOS R II is the camera we should have had from the beginning, and it's absolutely no surprise it's coming next year.