I'm convinced 8k60 is pretty much a given at this point. The R5C showed that the sensor can handle it, but that the Digic X needed more juice than a LP-E6NH can supply. The R6II and R8 showed that the Digic X variant they are using only needs half the power compared to the R5/R6.
So a current R5 with the Digic X from the R6II would very likely be capable of 8k60 with AF using just the LP-E6NH.
Personally, I'd like to see all the improvements from the R6II show up in the R5II: tracking in all AF modes, auto subject detect, no 29:59 video limit, HF flicker reduction and FPS selection. And a much improved sensor readout speed. Without an improved rolling shutter, the R5II would be a hard pass for me. Even with improved speed it would be a hard sell, it's not the R5 that's holding back my photography