I would love to read about a crop RF body yet I have not seen one single article. Could you point us to any credible info as to Canon rumors about them making one? I was under the impression aps-c wasn't in the cards. It would be nice for the 7D2 camp.
I think there is a chance that Canon is going to have two distinct lines. Ef-m for crop, RF for full frame.
Before about 2012 the tech made sense to put crop sensors with mounts that allowed people to mount full frame lenses, eg 7D with 400/5.6 made sense for birders especially those upgrading from entry rebels. But the higher resolution sensors now in full frame mean this is less and less important. The costs of full frame sensors have come down hugely. For birders there will remain an advantage perhaps but I think it's no longer such a big deal. And with lower price full frame cameras the typical upgrade path doesn't necessarily now start with a crop camera. I might be wrong, Thom Hogan, who I respect, in every single article about Canon goes on and on about how it's a huge mistake to have two distinct lines because people like him love to put full frame telephotos on crop cameras.
So what advantage is afforded by two lines? Size. If you pick up and hold one of the Ef-m cameras you might be shocked how tiny it is. For most consumers, price and size remain the two key things - especially as smartphones get better. So if Canon can produce tiny crop sensor cameras for the mass market this might be a good trade off. Canon always has an eye on the consumer market and the professional too - so we are really talking about a product line for each.
The alternative was a single mount. If they took the Sony approach of a smaller mount it makes some lens design a bit more difficult - of course they can have 0.95 lenses in Sony (and Leica M) but from what I've read the design is more complex. It also results in weird ergonomics with big bulging lenses going to small mounts. Indeed Canon actually said that with the RF 70-200 the larger mount allowed them to position the optics to allow for fewer elements and lighter weight.
There is the Nikon route of putting everything through one giant mount. That does allow easier full frame lens design but it means there is a limit to how small the cameras can be and they become quite ungainly, dominated by a big mount in the middle, eg the Z50.
The particular pattern we had from 2000 until recently where because of cost and legacy lenses many people mixed full frame glass with crop cameras was always a bit strange in some ways though it made sense.
Personally I think if Canon has split the lines permanently that is likely to be a good decision, both for ergonomics and price point but also because it means one gets the "right" size mount for a given sensor. How many people really today are choosing between an M50 and an R? I think outside some birders it won't be many and if Canon really does come with a 60/70+ mp Rs they would likely be better served by that.
Just my thoughts - and as I said plenty of experts think Canon has got it wrong but many of them, in my view, are looking at it like it will be 2005 forever.