This
"Canon does not need another $10,000-$15,000 big white lens."
and this
"The current versions [ RF 400 F2.8 L & RF 600 F4 L lenses] were designed for the EF mount, so it's time for native RF mount versions."
Interesting seeing the author disagreeing with himself...so I don't have to.
I agree with the latter quote although I'm unlikely to be a buyer (I'd need to sell my Nikon version of the 400mm f/2.8 first), but there are a lot of Canon shooters who are unhappy with the converted EF lenses. Sure, their IQ is excellent, but an RF lens built for mirrorless would probably provide some weight and size benefits not to mention the potential for a built-in TC.
I am interested in the 300-600mm. I prefer to travel with my Canon R5, but it would be nice to pair it with a (relatively compact) lens that is stronger for wildlife/birding than the 100-500mm (a lens I love but often wish for more).