High mileage assignments? The R5's shutter life is 500k actuations (same as 1DX iii) compared to 150k for the 5Div, 200k for the 7Dii and 300k for the R6. Using the eshutter doesn't affect the shutter life of course.
I contend that the 7D series are a marketing unicorn with fast fps, weather sealing, dual card and top AF in a relatively cheap body. I can't see all these features coming in a R7 body. All these features are already in R5/R6. A crop sensor would have a cheaper fab cost than full frame but I can't see that translating to a big price decrease compared to the R6.
I'm just not convinced that there is a big enough difference to the R6 to warrant a R7 and the required new RF-S wide angle lenses that a crop sensor would need (10-16mm plus maybe some primes). Alternatively, Canon may say to use an ef-R adaptor and EF-S lenses.
The only benefit for a crop sensor over the R5/R6 would be if there is a greater pixel density. Perhaps a crop version of the R5s' sensor.
At the time the 7D Mark II came out in 2014, the 1D X had a shutter durability rating of 400,000 actuations. But the 5D Mark III, and the 5D Mark IV that followed in 2016, only had 150,000 ratings. The 1D X was 18 MP (giving only 7MP cropped to APS-C "reach") and the 5D Mark III was only 22 MP (giving only 8.6MP at an APS-C crop) and slower handling. The 1D X could do 12fps, the 7D Mark II could do 10fps, and the 5D Mark III could only do 6fps and bogged down in fewer frames than either the 1D X or 7D Mark II.
Yes, the 500K shutter rating, equal to the 1D X Mark III, and 12fps (mechanical) of the R5 does make the calculation a little different from comparing the 200K/10fps 7D Mark II to the 150K shutter rating/6fps of the 5D Mark III and 5D Mark IV. But who's to say an R7 is only going to have a 200K shutter? I would expect if we get an R7, it will have a higher shutter durability rating than the 7D Mark II. The R6, at 300,000, is quite the improvement over the unrated 6D Mark II and the 6D with a 100,000 rating. Perhaps the R7 would be somewhere in the 300K-400K range?
Any APS-C camera can have the same sensor transit time at 1/1.6X the same curtain acceleration/deceleration/average speed, or 1/1.6X the transit time at the same average speed. Using the same technology in the R6 shutter scaled down by 1.6X would give it a 1.6X faster transit time. Reducing the transit time to match the R6 would make it cheaper if using lower grade components or more durable if using the same grade components.
The R6, with a 20MP FF sensor that crops to only 8MP, is a non-consideration for the same use case when one would expect at least a 30MP APS-C sensor in any forthcoming R7.
Even if it is the same price, or even slightly more than the R6, many would be attracted to basically an R6 body with a 32MP APS-C sensor inside (giving the same pixel density as an 82MP FF sensor - that's a FAR cry from the R6's lower pixel density.)
Why would Canon make a scaled sown 18 MP version of the R5 sensor when they've already got a 32MP APS-C sensor used in the 90D and M6 Mark II? The 32MP APS-C sensor is much newer technology (2019 vs. 2014) and performs noticeably better than the "vintage" 20MP sensor in the 7D Mark II. Many of us would have bought a 90D if the 7D Mark II's AF system and the 200,000 shutter durability rating had been included. Instead, Canon chose to keep the lower grade 80D AF system in the 90D and give it only a 120,000 actuation rated shutter. It had the sensor we wanted, but not the durability we needed. The R6 has, perhaps, the durability - but it does not have the sensor we need.
Lack of wide angle lenses is not much of a consideration, either, as most 7D Mark II users used telephoto lenses on them and chose the higher pixel density APS-C sensor to get more "reach" from their telephoto lenses. For those who even do WA work, they used their FF cameras for that.
Not many who want an R7 want only
an R7. They want one R7 to supplement one R5 or R6 when higher pixel density shooting sports/action is needed for the "long" body while simultaneously using the R6/R5 as their "wide" body, rather than having to buy two R5 bodies or an R5 plus R6. Only if the price of an R7 gets close to the price of an R5 would it make more sense to use an R5 in crop mode as the "long" body and an R6 in FF mode as the "wide" body. But even then the R5 cropped to APS-C is only 18MP, rather than 32MP. That can be quite the difference when "reach" without spending a mint is a key consideration. Shooting high school and youth sports can cover the cost of a 70-200/2.8. It's hard to cover the cost of a 300/2.8, much less a 400/2.8, and have anything left for all one's trouble.
Given a choice, I'd rather use an R5 at 45MP (short body) and R7 at 32MP (long body) combo than an R6 at 20MP (short) and R5 at 17MP in crop mode (long) if the cost is the same. If I'm really budget challenged, I could use an R6 (short) and R7 (long) combo. I'd have two bodies that, together, give me most of what the R5 can do for only about $500-600 more than a single R5.