I don't really see the point of f/2.8 trinity any more.
1) We don't need it for viewfinder brightness.
2) We don't need it for autofocus. (In the 90s and even I think the EOS-1Ds MkI MkII MkIII, only the center AF point worked at smaller then f/2.8.)
3) We don't need it to avoid grain/noise or to freeze motion on moving subjects. (Current sensors are fantastically low-noise at high ISO.)
4) We don't need it to shoot still subjects that would otherwise require a tripod (50/1.8 on R5 shoots about as well at 1/2 sec as at any speed above 1/30)
5) We don't need it to make subjects pop from backgrounds. (It used to be that focus was never great, lenses weren't so high resolution, film was grainy, exposures were blurred by camera shake, and so even the SUBJECT was pretty blurry. Because of those factors, we didn't use images in big sizes. In order to make the background visibly yet blurrier at this low print size, f/2.8 sometimes helped to make the subject stand out. But now, we prepare every shot even for our personal social media to be 15" (38cm) wide. The sensors are practically noiseless. The AF is utterly nailed to the subject eyes. Lenses can do 50lp/mm or better at very high contrast. Sensors are noise-free up to ISO 4000+. IBIS saves us with camera shake. The subject is absolutely clear as a bell and even f/4 (wider shots) or 72mm aperture (tele) gives us more pop at these large image sizes than we ever got at f/2.8 in the old days.
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In reaction to the new 24-105/2.8, and the nice 15-300mm f/2.8 trinity it creates: I do get the utility of 24-105. For me I've been shooting 24-105/4 instead of 24-70/2.8 pretty much exclusively for 15 years now, despite shooting 24-70/2.8s since they were 28-70s... 24-105 is a a great shooting range. I even used the RF24-105 almost exclusively on my R despite having a half-dozen EF lenses in the cupboard.
I just don't see the need for f/2.8 for it though.
The EF MkI 24-105/4 was a good size but soft. The EF MkII was bigger and better IQ. I'd summarize the RF MkI as being the EF MkI size with EF MkII image quality. I'd like to see them make a higher image quality RF MkII, even if substantially bigger and more expensive, and I'd buy it instantly.
I do love the big apertures too like the 135/1.8 and would order a 35/1.0 or 35/1.2 instantly, for special projects, but I don't need f-stop bigger than f/4 or aperture greater than 72mm in general. f/4 and 72mm do everything I need to. For me the big question is: if you need more than f/4, and I agree such cases arise, how can f/2.8 be enough? If I really want to blur backgrounds or something, then I want not f/2.8 but f/1.4 or bigger.
