So it DOES extend. Not sure whether to find that idea thrilling ...
https://photorumors.com/2019/10/10/here-is-why-the-upcoming-canon-rf-70-200mm-f-2-8-l-is-usm-lens-is-so-small/
Well I wasn't sure there was a point in trying to hide that fact for as long as they have. I mean, once the lens would be shipping, people will know, right? Maybe they thought pre-orders would suffer?

It makes sense in the "lets drop the mirror so you get more compact" world, and it works well in the 70-300mm L and 100-400mm lenses. But will it mean (negative) focus breathing, like with the 70-300mm L? I hope not, not now Nikon has finally resolved its negative focus breathing issues with the 70-200mm lenses.