Well, my guess is that the 200-400mm f/4 obliterates the chances of a 100-300mm f/4 or a 135-400mm f/4-5. While I frequently use the 100-400mm f/4.5-5.6L, I'm not a fan of the push-pull design and it just isn't bright enough, but a 200-400mm f/4 is just going to be too far out of my price range. I wish there was a supertelephoto zoom between them.
I also wish for a more affordable stabilized supertelephoto prime. I'd settle for a non-DO 400mm f/4 or 500mm f/5 or f/5.6. The price jump between the 300mm f/4 & 400mm f/5.6 class and the 300mm f/2.8 & 400mm f/4 class is just too great. I'm not going to spend $4000+ for a big white prime or zoom, but if they offered something in the $1800-2500 range better than the current $1200-1600 offerings, I'd be interested.
In the realm of shorter glass, I'd like a 14-24mm f/4L. I want a nice quality super wide for landscape work. Since it will be on a tripod mostly and I have to hike with it, I don't need or want f/2.8 or IS on it. Plus, not being f/2.8 on something that wide increases the chances one could put a neutral grad or other filter on it even if it has to be a 100mm wide rectangular filter.
I expect we'll see replacements for the 45mm TS-E and 90mm TS-E sometime relatively soon. I've thought about pulling the trigger on the current 45mm a few times, but I'll likely wait to see what improvements are made to see if the new version is worth the $600+ price premium the new version will likely have.
As an other poster said, I've given up on them ever updating the non-L primes for digital. Several of them are over 20 years old and just don't have the resolution for digital. I already have a couple of alt lenses (one prime and one zoom) that despite their age do work well (the C/Y 35-70mm f/3.4 on a 5D2 is just magic). Canon needs to remember that not all of us want to shoot at ISO eleventy billion with an f/0.7 image stabilized zoom with a high zoom ratio. I know landscape photographers are not a huge market compared to the general market, but there is something to be said for smaller, lighter, excellent quality slower primes.