With your logic the 7D series was also not needed, a FF body size what a waste to put an apc sensor in it.
i do agree with you that for certain use cases - "focal length limited + action + budget limited" - APS-C cameras are still useful.
but i think/guess (!) Canon will meet that demand with a "higher-end" EOS M model rather than putting an APS-C sensor into its EOS R series.
And i see zero chance for a new lineup of crop-only "RF-S" lenses, just when they are about to transition from EF + EF-S to RF + EF-M and consolidate 4 concurrent lens lines into 2.
upcoming EOS M5 successor could be as capable as Fuji XT3 (= better than 7D II and Nikon D500) and come in a fairly rugged, weathersealed body that is
* a bit larger than M5 (more grip, stronger LP-E6N battery - like EOS R)
* but still smaller than (current) EOS R model and
* priced substantially lower than EOS R - eg 1299-1499 (again, competitive with Fuji XT3).
i believe Canon will clearly distinguish its 2 MILC product lines by imaging circle:
1. EOS R = "FF all the way"
2. EOS M = APS-C sensors, covering spectrum from entry level "point and shoot style" (M100, powershot replacement) all the way up to and including "80D/7D class" segment
But ... i am only a "market observer" for many years, not a Canon insider. We shall see, which route they'll really take.
Personally I always prefer "functionality with as little bulk as possible" = cameras with "large sensor in as compact/portable a shell as feasible". worst case for me is "a dwarf-sized mFT sensor buried in a giant camera that could easily house an FF sensor ... (eg Pana GH5).
i am hoping/waiting for the opposite ... a mirrorfree FFsensor Canon EOS R model as capable, but smaller and lower price eg 1599 to 1799. Ideally (for me) almost as compact as a Sony A7 first gen ... but with serious LP-E6N class power pack ... and with pop-up EVF (as seen on some Sony cameras) instead of "permanent hump on top". Minimum pack size (mountaineering) and inconspicuousness (street, concerts) are important for me.