After merging the two 1-series lines into one, Canon kept the 1D X series bodies at relatively low MP counts (18, 20, 20 for the three iterations). As I see it, Canon had three range options for the MP count of the R1 (past tense, because the MP count of the R1 is likely set):
- 24-36 MP – The R1 as a successor to the 1D X II/III to bring those users to mirrorless. If this is the goal, I'd guess something on the order of 30 MP, a 50% (numerical) bump over the 1D X II/III, higher than the R3, significant but not a massive change. This seems consistent with the original aim of the 1D X series, a combination of blazing speed and good resolution in a robust body. If they go this route, it suggests the R3 will not see a MkII but rather was a stopgap launched to accommodate those who wanted an integrated grip MILC before Canon was ready to call something a 1-series. Further, with a relatively low MP R1, I suspect they'd launch an R5s or something similar, relatively slow but with a very high MP count.
- 45-60 MP – The R1 as a hybrid camera, sacrificing some speed in favor of a higher MP count to support 8K video. If they go this route, it suggests the R3 is the first camera in a series of lower MP, highest speed bodies. This would amount to a tacit acknowledgement that they made a mistake combining the 1D and 1Ds lines.
- 80+ MP – The R1 as a high MP beast. Likely a substantial tradeoff in speed. Possibly they use a quad Bayer sensor like the newer iPhone Pros or the OM-1 (2x2 clusters of the same color mask) to allow RAW images at 1/4 the pixel count, but that means an IQ tradeoff when shooting full resolution so it seems unlikely to me for a 1-series camera. Personally, I doubt this will happen.
Personally, I suspect #1 was Canon's choice. It's the conservative choice, and that seems consistent with Canon's camera body strategy to date. Arguments that reference Sony and Nikon's higher MP flagships as a reason for Canon to follow suit fail to address
why Canon should follow suit. Consider instead that Sony and Nikon are releasing higher MP flagship bodies because Canon is not. Competing head-to-head with the company that dominates the market not often the best strategy.
From the comments on this forum, it seems many users here would prefer the second or third options. For those who believe opinions expressed here have any significance, review the number of forum posts expressing desire/need for the release of an RF 50/1.4, and before 2018 an update to the EF 50/1.4...and then consider Canon's complete lack of 'response'.