I would be beyond shocked if the R1 had a lower than 45 megapixel sensor with what we are currently expecting as a flagship body. There's been wild speculation at 100 megapixels and such online. I suspect it falls in the 45-85 megapixel range.
However. If the body is positioned differently and they plan something like an R1s, harkening back to the 1Ds days, I can see launching something lower resolution potentially and moving high resolution to another body.
R5 MK II. My hopes would be Canon building on R5's sensor design, but they could now make this high resolution platform while breaking off and created a new body to replace the R5C with a different sensor.
This is actually a difficult position currently as there is a demand for a higher resolution stills oriented camera as well as a new Canon Cinema EOS camera.
My real hopes in terms of the product line, whatever they are called.
- Build on R5's sensor tech, perhaps go to BSI, global shutter not needed just yet, allow for full 3:2 recording up to 60fps, perhaps 120fps in 17:9, this could be cinema camera.
- A very focused high resolution, high dynamic range stills RF mount body. I'd lean closer to the 75-85 megapixel realm given what's possible. 65-ish also not a bad choice.
There's lots of new in camera features I'm looking for, but I'll save that for another moment.
The R5 and R5C have been wildly successful and represent a very good value. Clearly these are things to build on. An R5C in say something closer to C70 body or a new C500/C700 class camera, but smaller, with internal ND would sell well if there are improvements to the sensor design for instance. And for stills the R5 as is wonderful, but for those who knew how to get the most out of a 5Ds or 5DsR or are looking at "middle format" medium format sensors for professional work, Canon needs to make up some space here.