Something I\'d like that no-one\'s mentioned is a 24-105/4 MkII. The one we have just is a serious notch below the 50/1.8, 100/2.8, and 100-500 (see my SHOOTOUT tests in this site\'s lens forum).
And of course the 35/1.2.
If they invited Sigma in with mirrorless-designed 14/1.4, 28/1.4, 50/1.4 and maybe 85/1.4, I don\'t think I\'d really need anything else until I die.
I think the R5 MkII and R1 are actually going to have features ORTHOGONAL to the usual measures of megapixels and frames per second. Canon patented a new type of sensor about 3-4 years ago (mentioned on this site) that could do global shutter, electronic ND, and nearly double the dynamic range. Having studied the patent I think it might also be able to adjust flash power after the fact.
Another idea is a sharpness-priority that keeps taking photos (or takes a movie) until the scene at the focus point is totally sharp.
Another idea is a 42x42mm sensor that captures the full image circle, allowing you to take landscape, portrait, or any angle in between without moving the camera, as well as other ratios besides 3:2 without substantially losing pixels, and be able to fix keystone distortion without significantly losing shot area.
The current IS is so good that I\'m getting the best photos out of for instance the 50/1.8 at I think 1/2 to 1/15 sec, whereas the 24-105 is best at 1/30-1/60. I\'d like to be able to program a P curve PER LENS.
Finally the only complaint I have about the R5 as it stands is battery life. I\'m wondering if at least we could have a low-power mode that allows the camera to stay on all the time, if not a double-size battery.
Those specific ideas might not be at all compelling, but should illustrate that there\'s lots of directions to go besides simply LCD size MP, and FPS.