I've seen 2 confident declarations of RF killing off M today. How and why? RF = high end, M = low end. It sucks that the two systems aren't interchangable, but they have a common bridge- EF mount. Plus honestly, even if they shared the same mount, most people going from APS-C to FF would be replacing a lot of lenses anyway. EF-S is 20 years old I think, and even when ILC sales were approaching 20 million Canon didn't see the value in fully developing the EF-S line. But they kept updating and developing EF-S nonetheless. So crop is always going to be the basic low end system with FF serving the higher end. Canon needs both ends of the spectrum. It just makes sense.
I'm with you on this one, except I don't even think it "sucks".
Canon based their strategy on their data, which was telling them that the much-vaunted aspirational upgrade path, where a new hobbyist buys into an APS-C body, but equips it with FF lenses, in preparation for moving up to FF bodies as they 'mature' as a system-based photographer, was simply a myth and didn't happen often enough to be worth designing camera systems around. I think the data was saying about 7% of FF buyers got into it that way (or was it 7% of APS-C owners moved up to FF that way?--not sure).
The other 93% were staying in APS-C, or buying their first FF bodies without already having FF lenses in the same system.
So what really happens, in terms of market realities, is that in general, photographers buy APS-C and stay there, in which case FF lenses are a waste of size and money, or move to FF bodies without regard for their prior investment in APS-C.
So the vast majority of people who buy M system are not on their way up to R. They are a different market and need moderately priced compact systems. Canon are delivering that.
Then we have FF buyers. Top FF systems are expensive, so Canon are providing cheap entry points to get them into this more high-profit segment, which makes sense because they and Nikon tried the up-sizing path with DSLR and the data showed it failed.
cheers