Canon EOS-1D X Mark III
I'm all onboard for the 1D X III. Despite transitioning to the Sony a9 for motor racing events, nothing beats the 1D X for wildlife, especially when the weather and conditions are cold, wet, and nasty or hot and dusty. Read: Svalbard, North Slope, Namibia. I've accidentally dunked my 1D X in frigid arctic water and used the others in pouring rain and blinding snow without a care or worry. Wouldn't try those weather conditions with the a9 for the love of money. However, when the weather is great, the 20fps of the a9 in complete silence is outstanding to behold, especially when compared to the machine gun firing of the 1D XII at 14fps.
Canon EOS RX
The RX is, for me at least, too little, too late. I have too much investment in Sony at this point, given they're just released two new supertelephotos. I worked the Chevrolet IndyCar Detroit Grand Prix this year and even limited to the Sony 100-400mm and the 70-200, I never missed my 1D X II (though the thunderstorm on the first day's afternoon gave me concern, but since the Marshalls evacuated the track, I missed nothing).
Canon RS
For me, this is a real hair-puller as I love my 5DSR for landscapes. It was also my preferred body for studio model photography (art nude, implied nude, full nude, adult) but this camera was set aside with the advent of the Sony a7RIII with facial focus and eye-capture. Besides, don't need weather-resistance in a studio. LOL
It's something to consider, and I would probably rent one and put it through it's paces. Landscape photography can see pretty crappy weather too, and my 5DSR has never complained. With my large stable of EF lenses, any performance reduction seen by using the adapter wouldn't matter in landscape. 60mp might justify trying out a few RF lenses.
EOS M
These were my first mirrorless, and I bought the M, M2, M3, M5, and M6...with all the Canon glass. Now Sigma announced three (3) lenses for the M-mount, so apparently somebody believes—if not Canon—in this camera. They'll never be a prime camera for me, but in a hip holster they weigh next to nothing and can be in my hand in seconds.
Yes, I probably will spring for the new one, depending upon the specs.