Canon has had their foot on the gas ever since the release of the EOS R5 and RF 28-70mm f/2L USM lens. It looks like they have no intention of slowing down, with two mightily impressive lenses likely on the way soon.
Digicame-Info discovered two lenses that have been added to dealer lists recently, which indicates an imminent release. The lenses are the RF 800mm f/5.6L IS USM and RF 1200mm f/8L IS USM. It is no surprise that an 800mm f/5.6L is coming to the RF mount lineup at one point or another; the EF version has long topped out the revered line of professional supertelephotos that ranged from the 200mm f/2L up to the aforementioned lens. As such, an RF version has likely been planned for a while, and now that the RF 600mm f/4L IS USM and RF 400mm f/2.8L IS USM are available, it seems a logical next step.
On the other hand, we have not seen a 1200mm lens since the famous 1200mm f/5.6L, and that lens had an extremely limited production (it's rumored that only about 20 copies were ever made). As such, a new 1200mm lens could be quite exciting and would be a very interesting offering for a range of photographers. We'll see if the next few months bring an announcement!
I'd much rather see a 200-500 with built in 1.4 along with a new 500mm and 200-600 zoom to fill the gap. A 1200 F8 is too slow and would not impress in low light.
An 800 F5.6 isn't anything to write home about as you get 840mm @ F5.6 with a 600/1.4... unless, however, if they reduce the weight substantially for hand holding.
I'd have thought a 500mm F4 and 200mm F2 would have been higher priority.
A 1200mm is going to be a rarely seen. It's potentially little more than a 600mm with built-in 2X extender. Same with the 800mm. I think a 600mm with extenders is a more flexible option.
For me Canon should bring out a 200-600mm lens, something similar to the Sony lens.
On one hand Canon are aiming to bring out cheaper RF camera's but bringing out ultra-expensive lens.
They need to bring out some reasonably priced lens to match the cheaper cameras.