When the Canon EOS R3 was announced, it came as a bit of a surprise. It was Canon's first foray into a “professional” camera body for sports shooters, photojournalists and the like. Canon was adamant that the EOS R3 was not their flagship, and that would be coming in the EOS R1, which is scheduled for finally launch in 2023.
There have been some reports that the EOS R3 line is “one and done”, but that doesn't appear to be the case. We have been told that a Canon EOS R3 Mark II is planned, and it will be differentiated from the EOS R1 is a lot of ways.
With Sony announcing the global shutter A9 III and rumors that Nikon will also release a “speed demon” camera of the same ilk, we think it's safe to assume that Canon will do something similar in the EOS R3 Mark II.
This is pretty far in the future, and any sort of specifications are obviously not decided at this time. We also implore you not to make buying decisions about the EOS R3 and waiting for the Mark II, the EOS R3 is a great camera today and you'll be waiting a long time for the follow-up.
We trust where this information came from, but treat it accordingly.