That's been Canon's strategy for a while though I think the underlying reasons behind this have more to do with the technology and data processing/management than anything else. If Canon could produce a stacked sensor with 40+ MP and high DR, and fast read out, and offer 120 FPS, pre-capture, etc. all at a reasonable price, it would be in the R1. They can't that's why they are offering a lower MP "flagship" and a higher MP body which will be likely crippled in some regard for everyone else.
The original R5 was a bit of an anomaly for Canon because it was the first body which deviated from the traditional Canon strategy. Yes, in the days of the 1d and 5d series, your theory largely held true and for example if one looks at the contemporary 1dxmkii and 5dmkIV the differences in performance were significant. Although the cameras shared some similarities (61 AF points), the 1dxmkii had a much superior AF system and 2x faster FPS. The 5dmkIV was a great camera but it couldn't perform on par with the 1dxmkii for events where critical AF and speed were needed.
When the R5 was released it was groundbreaking for Canon. Suddenly, Canon users had a camera which could deliver a high FPS, and accurate, flagship like AF. Quite candidly, when the R3 came out, I didn't see a need to purchase one initially because the R5 performed so well for sports, WL, portraits, and nearly everything else. After purchasing an R3, I sold it in favor of another R5 body because the better battery life, real time EVF, and slightly better AF of the R3 were offset by having two similar bodies, a smaller form, and 8k video. Plus, I could buy another lens with the price difference.
So, what do you think the R5II will bring which leapfrogs the Z9 (I think you meant Z8) and A1? Based on the current rumors, at most they'll achieve parity. Again, I seriously doubt that Canon has brought to market a similar MP, stacked sensor, with magical properties. Perhaps they will? Also, it's difficult for me to see how the features of the R1 suddenly take down the A9III or even Nikon's Z9. If these bodies achieve parity with Nikon/Sony, then Canon users can breathe a sigh of relief. Quite candidly, if Canon had refreshed the R5 with a stacked sensor with a fast read out, affording real time evf, and reducing RS, improving the 8k runtime (which they've supposedly done in improved heat management), offered real-time zebras for stills (? doesn't appear on the table), and put in the R3's AF, it would have been fantastic. But it took them nearly 4 years to do so and in that time, in addition to releasing a pair of really top notch bodies, Nikon has also presented an amazing series of affordably priced, lightweight, high quality prime telephotos. So even if the R5II is all that, one is still stuck with either purchasing lower end glass, or selling their first born for a large, f/4 600 mm. No thank you.
