Supposed, maybe, but it's pretty clear that the R10 is not a xxD successor but a step below. A spiritual 77D successor I would say, even though Canon's new tech mean the AF and burst speed are totally unprecedented at that level. Taking the names too literally only serves to confuse.
People are just too hung up on the word successor. I think Canon has made it clear that the R7 is the mirrorless camera
that occupies the same place in the canon lineup as the 7D series did in the DSLR lineup. It is the higher end crop camera. Not as high as many 7D users would like, clearly, but this is the position it occupies whether you like it or not. The R10 occupies the position in the mirrorless lineup that the 90D does in DSLR. A mid-level crop camera. Anyone looking at the price can tell it is not a Rebel replacement, and yet people continue to stupidly make that claim. Of course, the market can change - and may continue to do so at a more rapid rate than camera companies want, but that's the lineup for now. Will their be a "Rebel" crop RF mount camera. Only time will tell, although I think it will inevitably happen. Will there be a higher crop camera than the R7? Seems quite unlikely as Canon is categorizing this as their high-end crop camera.
I'm sure the executives at Canon are shaking their heads. I'm sure many thought that giving essentially the same numbering scheme to the new mirrorless lineup would make it much easier for Canon users to transition and know where the new cameras fit into the lineup. I'm sure they thought that consumers would be smart enough that these are all new cameras and mirrorless represents an opportunity to tweak and modify what sort of spec list would go into each level and what price point was appropriate. Boy were they wrong!
So far, it seems pretty straightforward:
1= highest priced flagship (yet to be seen)
3=next in price
5=next in price
6=next in price
7=next in price
8=?
9=?
10= lowest priced (so far)
Now, we believe there will be an R and RP replacement, will they become the R8 and R9? I have no idea. Will their price necessarily fall between the R7 and R10. I would say no, not necessarily. But I think the general pattern is pretty clear.