I used to shoot with a 1D X before migrating to a R5.
I still miss the ergonomics (apart from 1 thing: I absolutely adore the 3-wheel setup of the R5), battery life and the feeling of indestructibility. The R5 wins on AF, resolution and I love some of the new RF glass.
Because I want high resolution (like the 45mp on the R5 a lot, like the 80mp on my IQ1 80 even more), the R3 was not on the cards for me, even if I like a lot all the rest of it. Yes yes I could survive with the 18mp of the 1D X, but, for me, more resolution is better any time.
Video is not important to me but nice to have. For me good AF in video is more important than resolution and the R5 already does great for that.
So, depending on specs, I am definitely interest in the R1, even though I am not in a hurry since a) the R5 is great and b) I will already spend on the future (?) new RF fast primes
Give me 80+ mp, even better AF (maybe with the eye AF of the R3?), at least as fast as the R5, body similar as the R3, even better viewfinder, and I am in