So I can tell you right now, as much as I want a massive resolution increase over the current 1DXIII, it will prevent many photographers from buying it. Unless Canon comes out with a better alternative to cRAW and allows us to shoot in smaller, more preferred resolutions, I and many others will struggle to justify making this our $6,000+ camera in the bag.
Why?
I was one of the first photographers in "my little slice" of the publishing industry that bought the R5. Several friends waited for my results before they pulled the trigger themselves and many of them shared my same criticism - 'I don't need 45mp to cover a race/event/wedding/real estate, etc.' I was quick to identify this and purchased the R6 to partner with my R5. Weddings in particular don't benefit from 45mp, it's more of a burden than anything else. At least in motorsports photography I can use that resolution for additional flexibility for cropping, in print or advertisement...but there is zero value in a 8192 x 5464 pixel dancefloor shot or cake cutting, so I lean on the R6 after the portrait session has concluded.
This is something many of us identify as a shortcoming of the R5 and it's rather upsetting. I hope that Canon reconsiders the importance of cRAW and can bring back an mRAW format that keeps things in the 12-15 and 20-26mp sweet spots. The argument of always shooting at the maximum resolution isn't exactly true for all of us. When I cover events I can shoot thousands of images a day for 3-4 days at a time and have to turn those around same day...and I still want the benefits of RAW, just not the resolution or file size. Yes, cRAW is roughly the size of a standard 20mp RAW out of the R6, but those images do NOT process easily in software like 20mp, as it chugs along to read the 45mp file format, versus blazing through a normal CR2/CR3 RAW...not sure why, but please give us back smaller RAW.