For the price to come out right, any time you go faster on fps, you have to increase buffer size AND limit file size, which usually means low megapixels. This is digital camera engineering 101. Faster fps trends towards action shooters and sports shooters, while slower fps allows for longer bursts and larger files, trending towards landscape shooters and commercial shooters.
30mp would be about right, considering that it is 30fps. The BSI probably allowed them to go from 30mp/10fps to the aggressive 30mp/30fps. People may remember that the 5DSr, which had a big jump in resolution and file size, had to take a huge hit in fps, and also they had to DOUBLE the DIGIC processors. ISO and video was 5Dm2 quality.
Even with all of the advances including BSI and extra lens contacts, it would be very unlikely for Canon to produce a 60mp camera that can do 60fps and 100-shot bursts in RAW. They can probably do that at this point, but the camera would cost an easy $10k, and at what size to dissipate the heat?
As far as 4, 6, or 8k goes, I would not look for them to do much. If I pay $6k on a R3 camera, by Jolly it better be still camera-focused and it better specialize in taking the types of stills I want to take, and forget about the video or how many Ks it does or C-Log or whatever. If I want to do video, I will do it right and get a C body. If I want to v-blog, I'll go cheap and get an RP. I would expect Canon to put out a half-crippled 5-series camera that does good video and good stills, but not great at either, with lousy ISO and lousy fps - a camera perfect for the peasants that require a camera to do both. To expect the R1 or R3 or R5S to do anything decent regarding video is outrageous and silly.