I have to disagree.
Canon has an interest in maintaining two product lines if they cannot successfully migrate existing customers to the new line. The camera market is shrinking and they can ill afford to just write off even 20% of their embedded customer base, so if they find they are going to lose loyal customers with high levels of disposable income they will adjust accordingly. I doubt if Canon knows the answer to that at this time and are probable hedging their bets.
Why do you assume the R and RF line is more profitable? You are equating profits with cost, but they aren't the same. The R and RF lines are more expensive, but the profit margins on the EF line are likely much higher since all the development and embedded costs have long since been paid for.
I'd like to see what heavy incentives Canon is offering to convert users to the R line. So far, I'm not seeing any incentives to customers. The R and RF lines are more expensive and there have been no rebates or other incentives offered that would reduce the cost to customers. Simply discontinuing EF lenses and DSLR bodies is not an incentive.
You make a few points that I don't see the same way.
The market is shrinking. But that does not mean that Canon has to focus on maximizing the absolute number of customers they maintain. Survival in a market niche isn't about size, it is about the relation between the prices customers are willing to pay and what it costs the manufacturer to provide the respective goods. It is better to specialize into products that are really profitable instead of insisting on capturing the whole market only to just scrape by. Currently, Canon has two seperate product lines that cover overlapping markets. There are both customers that are not interested in mirrorless for a variety of valid reasons (battery life, latency, eye fatigue, ...) and customers that are not interested in DSLR (just coming into photography from a smartphone, or prioritizing size over other aspects, for example). But for the most part, I believe the market Canon targets is just people who just want to take high quality images in an enjoyable fashion, and most customers will not restrict their purchase to either DSLR or mirrorless and focus on more important specs.
You say I am equating profits with costs, but I fully agree they are not the same. Although I believe you meant price there - which is also very different from profit, which I understand to mean price minus costs here. So why do I assume the RF ecosystem is more profitable? Well, for one that is what Canon seems to want investors to believe, since they use that wording in the financial reports I've seen. But it also makes sense just from this:
They have two product lines. There are a number of processes and components that they can share between both. The batteries, Digic X SoC, image sensor manufacturing, memory interface, etc. Then there are those that differ, like the specific tooling for the seperate body shapes and mounts, but at least the materials are the same. And then there are differing components.
Exclusive to EF are mostly the mirror, the seperate metering and focusing sensor assemblies. In the RF ecosystem, there are EVF screens, which aren't shared with DSLR, and technically also the IBIS assembly, though I'll get back to that later. While high density OLED displays are an improving technology that is also heavily used in seperate consumer electronics industries (smartphones, VR headsets, ...), the mirrors are a mature technology and for the metering and focusing it is just extra CMOS sensors for the latest generation of DSLR we've seen (1DX III, D6). Crucially, these are the components that need to improve to offer technical advancements in FPS and AF tracking. Given that even in their most expensive, professional tool Canon could not match the AF capabilities already found in the much lower end R6 (that is just a marginally newer product), I think it is fair to assume pushing the capability of DSLR AF is more expensive than even a 1 series customer base can justify.
In short, I'm under the impression that the components exclusive to the RF ecosystem are cheaper to source/produce and develop, than those exclusive to EF. If you have some differing view of that, I am interested.
As for lenses, it is simpler. The RF mount lifts some design constraints, making development easier or enabling new desings like the RF 28-70 mm 2.8 for more attractive offerings. And they have the benefit of being designed specifically for the current level of manufacturing technoloy and most importantly automation.
So with the assumption that the market for both ecosystems is largely the same and that the manufacturing costs exclusive to EF is greater than those for RF, that means two things:
- Most of the time, Canon will either sell an EF or an RF body. Meaning if they want to maximize profit, they should promote the more profitable one.
- With sales going down, there is more room to breathe in the RF portfolio pricing. For one, they have already established it as being more pricy. And the exlusive components are most likely being sourced externally and therefore not subject to as much economy of scale effects as the AF/metering sensors, which I assume are made in house.
So the more people stop buying EF, the more costly EF becomes to keep around.
There is another factor to consider with regards to the shrinking market. It is not shrinking the same way and for the same reasons at all price segments. On the low end, there is substantial shrinking going on, mostly due to people just not caring enough about IQ to justify spending and carrying so much over their already decent smartphone. And while also true for all other segments, saturation plays a role in the high end. With both the RF mount and RF lenses, Canon can stimulate demand somewhat just by offering something new and shiny that people can buy all over again. So while you are right that R&D for most of the EF lens portolio has fully been paid for, for most EF lenses the people who wanted one have already bought one. So mid-term you can expect a higher number of units sold for a given RF design, than the EF counterpart, lowering costs due to economies of scale. That's not what I meant with the incentives you questioned though.
While I disagree that 'crippling' EF (no eye EF update for the 1DX III in LiveView, no 7D III, no 5D V, ...) is not incentivizing towards RF, there are clear benefits to the RF system that elevate it above EF. You Get What You See is the classic one, but AF performance and mostly the IBIS are others. The EF image circle restraints and the mirrorbox, as well as the issue of misalignment between the OVF image and the sensor image mean that IBIS on EF would have never come close. For AF, I already discussed it. And of course the exciting lens designs that the lack of equivalents in EF (or other DSLR mount) indicates would not have been feasible otherwise.
I could elaborate further, but I think I have made my point. In any case, Canon has not shown much effort into keeping EF customers optimistic about the ecosystem. I think they very much have made their choice, and if you are unstatisfied with my explanation for that, attempting to get in touch with someone actually involved in the company would be you best bet for getting a more meaningful one, I think.