The EOS C70 has a crop factor that "varies" (4096 or 3840 4K pixels) if you measure the diagonal or the width, between the size of an APS-H 1,37x to APS-C 1.5x sensor, that's bigger than the "past" cameras from Canon, 1.6x crop EF-S lenses (and EF-M), APS-H never had a dedicated lens mount, it just used FF lenses (if we exclude Cine lenses).
Canon already makes an EOS R 0.71X speed booster for FF EF lenses that is roughly equivalent to 1.4X crop factor (similar to the APS-H from the past), the de facto Super 35mm film from the cinema industry, this could be an hint, Canon should stick with this "useful" crop factor also for the future EOS R7, as someone already said in this thread, some Canon RF lenses like the 24-240mm or the 24-105mm F4-7.1 have a reduced image circle that could fit well with a crop sensor and 1.4x seems more appropriate than the "old" 1.6x crop.
Canon RF extenders aren't anymore as versatile as the EF extenders, no more 70-200mm compatibility and even with the new 100-500mm it's less practical than it was with the 100-400mm, but if the future R7 is just a mini R5 (or R3) some photographers could like to use a digital extender instead than an optical extender (even if it's much more expensive), in the past birders and any photographer searching the extra reach used the 7D and similar cameras just for this (and macro), obviously to make this trick work the future EOS R crop cameras should have a pixel number that is similar to the FF equivalent model, the future R7 to be considered a mini R5 needs to have roughly 45MP, otherwise the crop "advantage" is useless (the 7D was considered a mini 1Dx an both had the same amount of pixels).
If Canon don't want to make RF-S lenses (it makes sense) an APS-H 1.4x crop sensor is the way to go, the EOS R to EF 0.71X adapter already exist, Canon could make an RF to RF version too.
An R7 with 45MP sensor like a mini R5, but at a price point that is lower than the R6 could be a massive success, many photographer just want a pro body without the need of a FF sensor, I think many 7D and 7DII photographers, but also 40D 50D 60D 70D 80D and 90D shooters looking for an "upgrade" to mirrorless will love to buy such a camera, it could be the first step to RF mount before eventually upgrade to FF.