Totally depends on what you shoot and what the new Canon mirrorless specs are when announced.
From the specs that have leaked on the 1Dx3, it may be just a professional sports camera for most and if you don't already have CFExpress cards, that is going to add to the cost.
The Canon EOS R is a nice camera and would be good for portrait work with the eye detect feature. (I've actually shot that one).
I'm very interested in the mirrorless market at this time because from what I see, Canon is killing it with the glass for the R system.
Since I shoot more sports than anything, I am waiting to see what "Pro" type stuff is heading. (Or I mean announced or is released).