I can see Canon responding with an EF 180mm f/2.8 L HIS USM.
Canon is so busy with cinema lenses, it can't make the super telephotos on schedule, bring out new TS-E 45mm & 90mm, etc.
How do you know this is the case?
Know what is the case ? That the super telephotos aren't in the shops on schedule ? That Canon started making new cinema lenses ?
No, how do you know that Canon "working on the cinema lenses" is slowing down production of everything else? It just seems like with all the natural disasters they have had on that side of the globe that naturally some things would be delayed. But I don't think any one product could be slowing down the release of another, you act as if Canon is only a handful of people working on stuff....
And why would they be in a huge rush to release their new telephotos? They hardly sell any compared to their shorter lenses, and it's not like they are releasing a focal length that isn't already available. Yeah, it's crummy that they are taking so long, but I don't think the production of the cinema lenses is SOLELY to blame.
Also, growing the fluorite crystals used to make the fluorite element that is present in all the current super-telephoto lenses, takes SEVERAL months, up to a year and a half for a lens such as the 1200/5.6L. It also takes four times as long to properly grind a fluorite element compared to a glass one. There are real process and manufacturing (and physics) reasons why they can't just crank out lenses like this on a moments notice, like they could for an EF-S 18-55IS II or something pedestrian like that.
If they started today, already having plans, and already having a factory tooled up and ready to go, it could take 6 months for the first lens to roll off the end of the production line. That's just how long it takes. Knowing this may also put into perspective how expensive these lenses are. It's not just purely a volume issue, production costs are huge.
Now, on a slight tangent. You have this very long, VERY sensitive, crystal growing process. What do you think happens when you throw a couple earthquakes, tsunamis, and a reactor meltdown at that process? I'll leave that speculation, as an exercise for the reader.