I think the problem here is none of us have access to Canon marketing / sales data. Plus I think there is an assumption here that Canon knows exactly where the market will go, and I don't think they do exactly (nor does anyone). The market is shrinking, and gyrating towards the photo enthusiasts & professionals. But while there is a market for people who want a little bit more than their phone can do, then Canon and others will operate in this market. Money is money after all. When that market dies, well then you have to have other revenue streams.
And as this forum shows, people want different things. The entry level market(s) are the largest. We have different smart phones, we have different bodies - be that a fixed lens/body with a standard zoom range, or a monster zoom range Powershots, or for a lightweight ILC (EF-M).
The R lens mount will eventually be the death of the EF development. EF lenses will exist for many, many years and will work on the R bodies, but eventually they will stop being developed purely for economics. Canon can do more with the R - either same size and cheaper, or faster and same cost.
The EF-M has those same advantages over the EF-S
dSLRs will exist for probably the next generation, and then they will also no longer be developed. So I think there will be a IDx mk III for 2019/2020, but by the 2024 Olympics there will be a mirrorless only. And frankly it will look very similar to the 1DX, but it will be cheaper for Canon to manufacturer. I put the 5x in the same category.
So that leaves the APS market which I might try and put into 2. The entry level and the Prosumer level. Perhaps the 80d/90d bridges those, but I don't think that it matters per se.
- For that entry level market I wonder how many EF lenses they own, and how many of those are Ls.
- How many of the Prosumer market / Pro market (be that APS or FF) have bought a entry level SL2 or xxxx range?
- For the Prosumer / Pro APS, I wonder how many EF-S lenses they own and how many of those are NOT Ls.
- Finally, I wonder how many entry level do indeed transition, other than the sort of people who frequent here, and just how many of those lenses they put on their Prosumer APS bodies when they upgrade or replace them with nice L.
- I know people would like to have an upgrade path, but how many actually use it?
I presume Canon has a reasonable view on all of the above
[As an aside, the tablet & smartphone world has I would guess a similar impact on the computing world, and there are reasonable parallels]
I think that Canon would like to entice most Prosumer APS users to go onto an R body, and sure, with a R lens. They can take their EF lenses with them. Would there be a APS in a near identical body? Most likely, if they can drive down the costs sufficiently, and they can match the 7Dx functionality (viewfinder, AF, speed). If not in this generation, then we will see a 7D III and the IV will be mirrorless.
I think the entry level APS is the most interesting, and I wonder if Canon sees the EF-M in that space, where people can take their EF-S lenses with them. And that very few go across to the R / EF space
Canon must, one hope, have sufficient data which resulted in the EF-M mount design and the R design being (intentionally) incompatible. Ultimately I don't think they truly know, but they are hoping that the segmentation of the EF-M due to incompatible lens mounts isn't going to hurt them.
Finally, I am guessing part of the reason to go for the 6DII or perhaps what everyone feels should have been the 6DII is because they are still developing / stabilising the tech for the higher end and also testing the market. And it's the market and the data they must be continually watching which helps them decide what happens and how the strategy will change. I would guess they have designs which can be either mirrorless or dSLR style, again depending on how well they see the initial R sales go. And of course that isn't just the APS side, the same in the dSLR side.