Here’s some speculations just for the fun of it.
Question: What are likely specs for the R8? To answer this, we need to figure out what is in the R6 mark II that would make it worth $1k more than the R8.
First, sensor. There are two approaches – either develop a new sensor that is at best as good as the R6, or to re-use, probably with some tweaking, existing sensors. Given that the R8 is priced between the RP and R, and that the strategy for them was to use sensors from previously advanced sensors in their respective price class, it seems more likely that the R8 would use an existing sensor. Also, again given the R8’s pricing, it is likely positioned as a replacement for both the RP and R, with possibly a sub-$1k FF body in the future. This way, the gap to the next level of body, ie. the R6 mark II, becomes clearer, rather than confusing the marker with another R mark II that is close to the specs of the R6 mark II.
To reuse an existing sensor, the 26mp RP sensor would have a perception issue for a higher priced body to use a lower priced body sensor, so it is unlikely. That leaves the 30mp R (itself reused from the 5DIV) and the 24mp (from the R6 II). Both are possible, and I am leaning more towards the 24mp for the reason that this would somewhat future-proof the R8. The counter argument is that the R6 II just came out for its sensor to be reuse so quickly.
If the R8 is to be a ‘mini’ R6II, then where are the potential cost savings? My guess would be in the following – single card slot, RP-like body with the smaller LP-E17 batter, one fewer dial, no LCD top panel, lower resolution back panel and EVF, lower mechanical and electronic FFS (8 and 20 respectively?). On the software side, I assume that the video specs would be lower than the R6II, probably 4k cropped.
As for AF, I expect it to be at the R5/R6 level, not quite the R3/R6II level (but hope springs eternal). The reason is that for a new modern camera that is priced not that cheaply, using anything less would likely be a turn-off, affecting sales. Canon has already shown in the R7 that they are prepared to use advanced AF system even for a moderately priced body.
Whether there is IBIS could be interesting. If the R8 carries the R’s 30mp sensor, then it is more likely to have IBIS than if the 24mp R6II sensor is used. Or perhaps Canon decides to make the R8 more attractive by throwing this in as well. Also note that if IBIS is included, then it would likely be a larger body (closer to the R, R6) with the LP-6N battery.
With a sub $1k body to come, the positioning of R8 to replace RP and R makes sense. It is also a useful ‘dumping’ ground for advance tech from R5/R3 etc so that these techs can extend their shelf-live to make them more profitable to develop. For someone upgrading from an entry-level FF body, the R8 would be attractive.