There is only one hand and this list has no hand. This describes a video centric camera. They might make it mirrorless but they will not make it something other than what the 1 line was intended. I laughed out loud when I read those specs.
The list is a hybrid between current 1DXiii specs and R5 specs.
It describes an excellent stills machine from R5 and improves on video capabilities from R5 (mostly thermal) with a new sensor.
Dual processors have been the case with 1DX ii and there is space for 2 processors in a 1D body
Dual Digic X would provide the horsepower for
- the oversampled video and
- 16fps downsampled 45->~20mp stills to meet the existing 1DX user base's requirements
IBIS for full frame is already in R5
9 megadot EVF from the A7Siii
Flippy screen already in R5... would mean a redesign of 1D body
Canon's engineers went completely out of (over!) the box with R5. If we saw the R5 spec list (even with thermal limits) 6 months ago, everyone would think we are crazy. It is amazing even now!
The 1DXiii specs are similarly great and would need to improve to have migration from 1DX users and R5 users. 1DX users don't need/want a smaller body and would accept the same weight but prefer less. Reducing the depth of the 1DXiii due to pentaprism and separate (heat generating) OVF metering sensor is a possibility but the space could be used for thermal dissipation as long as space around the lens is sufficient.
The biggest assumption on my part is the sensor being 8k (~45mp) with a faster readout for 16fps mechanical and less rolling shutter for 20fps and video. The rest is processing power, thermal management and battery life in a 1D body.
Why not!