I've got an R5 coming on the Canon Test Drive scheme along with a 24-70, 70-200, and 600mm to try it out. I'm not convinced we're going to see anything before a D6 replacement, which is going to be £6K+ and a price I can't justify. The R5/6 right now look to be way ahead of the Nikons in a lot of ways and the RF glass looks to be just as good as the S line lenses too.
I'm going to use the test drive, then give Nikon a little longer to see if they get their act together but I can see a switch in my future right now.