I don't get it. A pro-grade standard zoom that only mounts on a consumer mirrorless body. Everyone is going to give up their one series and 5 series bodies and buy a couple of R bodies, (cause you can't put these on your old camera as a backup) for these couple of lenses. I know Canon is the 800 lb gorilla but this is pushing it.
Canon have been pretty clear that the R body is not the big thing. The RF mount is. Bodies come and go. A professional R body will come in due time. Those RF lenses released now will last for a decade or two.