What many people miss when they are speculating about a new 1 series is that it is limited by the processor speed and there are just certain things Canon wants the camera to do. Some of those things are not obvious. I would imagine that at the very least it will be as good as the R3 at handling rolling shutter. I would speculate that any sensor put in the R1 would read as fast or faster than the R3. That said speed limitations will probably negate an extremely high MP camera, but not in the future. Canon will most likely not take a step back on any spec.

My guess is a body in the 32mp range.

I expect to see improvement across the board. The R3 has impressed me, so much so that the R1 will most likely be a pre-order when it comes out.

Frame rate? Is 30 fps not enough?

Maybe by the time it comes out there will be a 120mp R5s R as well.