I wonder if the 250 F/2 would come witha built in 1.4 tc?I'm pretty sure there's no reason there can't be a 250mm F/2, and I'd definitely be more interested in that lens than a 200 F/2. I use a 24-70 and 70-200 for night time breaking news, and the 300mm f/2.8 isn't enough extra reach to make me wish I had it, but adding a stop of light and some extra reach would make a great case for keeping a supertelephoto on me for night work. Canon also has been focusing on making *all* of the RF lenses have something special that puts them over the top of EF lenses, so I'm confident this lens would make sense.
A really, really great night sports/news combination would be RF 28-70 F/2, RF 70-135 F/2, and RF 250 F/2.
As for the 500mm f/2.8, now that's fascinating. If Canon can apply the same design principles of the EF 400mm F/2.8L IS III and the new 600mm, this might not be all that heavy of a lens. Maybe with the new lens designs they could pull off a 500mm f/2.8L IS that's only as heavy as the old 600mm F/4L IS? Add in DO or other designs and maybe it could be very manageable. This would be a dream lens for football, I know a lot of photogs who shoot with the 500 F/4 or 600 F/4 and sacrifice aperture for reach.