First of all, only Canon themselves know what's coming.... and they aren't saying until it's ready for the market. (It would make no sense for them to reveal their future plans to the competition.) So we are talking about RUMORS, which are easily spread these days, thanks to the Internet.
I think it very unlikely that Canon will ever offer an M50 Mark III. They're concentrating on the R-series cameras and the RF lenses for them. Those can be expected to replace both the Canon DSLRs (EF/EF-S mount) and the older M-series mirrorless (EF-M mount), as well as the lenses for both those systems.
From a business perspective, it just makes sense to consolidate everything into the new R-system, rather than building three parallel systems of interchangeable lens cameras with limited cross-compatibility. (You can adapt EF and EF-S lenses onto both M-series and R-series cameras... but you can't adapt RF lenses onto anything other than the R-series cameras. Likewise, EF-M lenses cannot be adapted for use on any other system.)
In fact, one could argue that the new R10, just introduced and only actually in stores for about 2 or 3 weeks now, is the equivalent of an M50 Mark III, but with a much more comprehensive system of lenses and accessories.In the ten years since the Canon M-series were introduced, there have only ever been eight Canon EF-M lenses and minimal 3rd party lenses (Quite a few manual lenses, but I know of only six that offer autofocus... three each from Sigma and Viltrox). In contrast, in the slightly less than four years since their R-series were launched, Canon has introduced thirty RF/RF-S lenses ranging from 5.2mm fisheye to 1200mm telephoto. Many of those lenses are quite innovative, too.
The R10 is slightly larger and a couple ounces heavier than the M50 Mark II, but both are 24MP mirrorless cameras with a shutter speed range from 30 sec to 1/4000, and both use SD memory cards. The R10 can shoot at 15 frames/sec. with its mechanical shutter or 23 frames/sec with electronic... compared to 10 frames/sec that the M5II can do. The R10 has a much more advanced AF system. Both cameras can shoot 4K video, but the M50II has a 30 minute time limit, while the R10 is only limited by the size of memory card and its battery charge. The R10 uses a slightly larger LP-E17 battery (versus LP-E12 in M50II) and is rated to get about 50% more shots per charge with it.
Yes, the R10 is more expensive. Some of the premium RF lenses are pricey, too.. But there are also now quite a few fairly affordable RF lenses. Two RF-S lenses were introduced along with the R10 and R7,. the first two APS-C format cameras in the R-series: an RF-S 18-45mm and a more premium RF-S 18-150mm. Of course, both the APS-C cameras can use all the full frame capable RF lenses, too... although of course there will be some cropping of the image.
There's more... I recommend you do some searches and research online to see for yourself. If you are wanting an M50 Mark III, it might already exist but is called the EOS R10 and part of the new R system... the system that will be replacing both Canon DSLRs and M-series mirrorless.
P.S. The Canon DSLR system has been around for over 20 years and is closely based on the film SLR system that preceded it by another 10 or 15 years. As a result, there are an awful lot of EOS cameras and EF lenses out there.... so it's not like it's going to disappear. Likewise, the M-series have been fairly popular, especially in some markets (I have an M5 and several lenses myself, as well as a number of Canon DSLRs and a lot of lenses for them). The transition to the new R system can be gradual... EF and EF-S lenses can be adapted for use on the R-series cameras (much as they can for M-series). Unfortunately, EF-M lenses cannot be adapted for use on any other system.
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Alan Myers
San Jose, Calif., USA
"Walk softly and carry a big lens."
GEAR: 5DII, 7DII (x2), 7D(x2) some other cameras, various lenses & accessories
FLICKR & ZENFOLIO
