That's possible - and other posters have suggested that the R3 was part of the original development of the R1, but was not quite at the standard Canon wanted for it's first mirrorless benchmark body under the R1 name. But, I wonder, if that was the case, why they would give it a 'new' designation - as R3? It seems strange to me to use a number like that for a one-off.
Canon may have decided that when they combined the 1D and 1Ds lines into a single 1D X, they made a mistake and with the R series it’s time to return to having two gripped/pro bodies. If so, the R3 is the ‘fast’ 1D in that analogy, which would make the R1 the ‘high res’ 1Ds.
It seems that’s the hope of some people here, though it’s not clear how many of those people would actually purchase an R1. Case in point, the aforementioned troll
@Cyborx who ‘lost patience’ with the 24 MP R3’s disappointingly low resolution…so he bought the 24 MP R6II instead.
It wouldn’t surprise me at all if the R3 is a one-off. Canon was clear that the tech was not yet ready for the 1-series designation (being honest, having my R3 AF fail in a subject with strong contrast because that contrast happens to be horizontally-oriented puts me in agreement with Canon on that).
I’m confident that Canon knows far better than the
@GoldWings and
@Cyborxs on this forum the MP count that actual buyers of the R1 want, and that’s what they’ll deliver.
For some reason people think the R1 must compete with the Sony and Nikon flagships (and not even the current versions but the next versions, at that), especially on MP count. It’s important to realize that brand switching is uncommon, and gets more so higher up the line. It’s also important to realize that Canon dominates the ILC market, especially the DSLR market that remains a significant majority of the installed base. Taken together, that means that the main target market for the R1 is 1-series DSLR owners, and secondarily owners of other high-end Canon ILCs. That’s a market for which Canon thoroughly understands their needs. History suggests a modest MP bump is warranted, not a big jump.
The wild card is the affluent amateur segment that’s becoming increasingly important. I suspect those folks are more likely to switch (no need for a business justification), are more likely to want to ‘keep up with the Joneses’, and I know some of them fall into the ‘having more dollars than sense’ category. If Canon gives that segment precedence, we may see a ‘high res’ R1 (45-60 MP). Not too high, though, because I also believe they’ll be an R5s at some point.