The 1DX Mark III and the future state of mirrorless

The 1DX Mark III is by all accounts, Canon's greatest achievement in an SLR.

However, what many are asking, where's the RF mount camera?

Many are pointing to the 1DX Mark III and stating that Canon is close, and there should be no trouble at all coming out with a mirrorless camera.  While the DNA of the 1DX Mark III will show up in the 1 series RF camera, Canon still has to do an incredible amount of work to ready that camera, which is why we most likely won't see it until 2021.

While the liveview specifications demonstrate right now where Canon is, where they are not is buried in one of the smaller points about the 1DX Mark III. While the CIPA rating for battery life through the optical viewfinder is excellent at 2850, little is mentioned that the battery life when using liveview plummets to 610 shots less than one quarter.

It's this battery life that is going to keep Canon's engineers working very hard on future cameras, even if they are the size of the 1DX Mark III and use the mammoth LP-E19 in the camera.  If Canon wanted to make the camera smaller and transition down to the LP-E6N battery, the problem would be even greater.  The LP-E19 is 10.2V at 2750 mAh - or around 28.0 Watt hours.  The LP-E6 batteries used in the EOS-R are 7.2V and 1865 mAh - or around 13.4 Watt hours.  So if Canon took the 1DX Mark III and put the same processing and firmware running in an LP-E6N camera, it would only support around 290 shots per battery.  

Sports, or 1 series users that would be transitioning from the EF mount to the RF mount using an 1 series RF camera, aren't going to be happy with getting 600 shots per battery in their new RF mount 1 series camera (half that with the smaller LP-E6N batteries) and this is where Canon's engineering comes into play.  As with your laptop, atypically the higher performance, the lower the battery life - a camera is no different.  Canon will have to optimize and balance the need for speed against the battery life of the camera.  They could even have to drop down performance from that of the 1DX Mark III to support a better battery life.  Canon I'm sure would be angst to do this, which is why they will most likely turn to create better efficiency in code, and also their DIGIC processors that they use for the 1 series RF camera.

So while Canon may be close to checking off all the boxes to a 1 series RF camera and it's exciting to see the new features such as the amazing video features of the 1DX Mark III, we should temper our expectations when it comes to the Canon RF mount - for now.  The 1DX Mark III has with it mammoth LP-E19 batteries that we may not see on the RF mount.  Certainly not for non 1 series RF cameras.