I'm eager to get mitts on an R5, and I hope Canon is able to get those out the door reasonably quickly, but Canon should be most worried about the R5 successor.
Canon has a habit of dropping the mic with occasional releases (5d2, 6d1, 1dx, 7d2) and then not paying any attention to the line for 4 years or so. And then, not letting that new version live up to the quite same notoriety as the original. A thing happens. People assume - wrongly - that because the 6d came out with better low light focusing than the 5d3, that this is part of the intent of the 6d line. Then, when the 6d2 comes out, people complain because it's not better than the 5d4. I hope this doesn't happen with the new R5 line.
Sony will probably have an answer to the R5. We should all hope that it does, and that it's fantastic. Sony will also probably come out with a successor to that new camera in only 2 years. Hopefully, this completely expected market condition will push Canon to target an update in a similar timeframe. One could argue that the R5 spec list looks like it might keep a performance lead for longer than 2 years without refresh, but I'm quite sure that's not the case - and that the fact that it's not the case is a good thing for all of us.
It's a good time to be a photographer.*
*So long as you're not concerned about being paid for it.
