I dissagree, the SD card slots in the current R6ii already cover 24mp @ 40fps more than adequately. The CF express is only required for high resolution 8K video. Which lets face it...is a niche requirement. if you need high end 8K...get a dedicated video camera that's capable of keeping the sensor and chip set cool.
I have no desire to swap over to CF express at the moment. It requires a new set of more expensive cards and a new card reader for pretty much the same feature parameters. Just because the R1/R3 and R5mkII have a CF express card slot doesn't mean that this camera should.
For me, I couldn't care less about the 14 bit super fast electronic shutter sensor read out speed if I loose out on the current model's DR and exceptional iso noise capcbility in 1st curtain shutter mode. Honestly 12fps 1st curtain shutter is mostly all speed I actually need or want. The current 40fps is total over kill.
A super fast sensor readout speed in ES mode puts this camera very close ot the R3 in terms of real world specifications.
What would I like as an upgrade? I'd like a top mount LCD and a higher rez EVF. Other than that....I'm super happy with the current R6ii.