Except nowadays you can use your higher end lens (EF) on a lower end APS-C bodies. Lots of ppl are doing exactly that imo. We did that too, with e.g. Sigma Art and Canon 70-200/2.8 II IS. We did this investment planning to enter FF one day. And we did so with the 5DIV.No, EOS M line has never been really in question. Only some folks like Thom Hogan and a few n00bs who are unable or unwilling to understand Canon's transition from 2 mirrorslapper mounts (EF, EF-S) to 2 mirrorfree mounts (RF, EF-M).
EF-S is dead. EF is legacy. RF and EF-M will be around for many years to come.
Your newly envisioned future of EF-R and EF-M only, removes that possibility though. For a brief period of time I thought, that Canon is going to scrap EF-M mount altogether, and introduce APS-C MILC with EF-R mount. It would be a tad bigger of course, but there would be just one mount, with an EF compatibility. But with recent addition of fast 32mm EF-M lens, it seems that Canon is commited to EF-M too.
On the zero transition possibility between the EF-M and EF-R - "well done", Canon ....