I feel like there's a lot of wishful thinking going on in this thread. No criticism of anyone in particular, but it feels like those people who really want a successor to the 7 series are asking for a unicorn. Even if the 7D was that unicorn at the time, I don't think it'll happen again - though I don't quite know why I feel that way.
What I would ask generally though, is this - we were told a while back that both Canon and Nikon had abandoned this segment - there was to be no 7D3 and no successor to the D500 was planned either. The implication was that the high end crop market was too small, and in the face of rapidly shrinking sales overall, its time was over. I don't know who originated that line of thinking, but I recall official sources being cited. Was it just a lull? Has a change of thinking occurred? Was Canon always preparing to transfer the line over to mirrorless? Or are we wrong on what this new body will be?
It seems that nobody has a firm idea of what to expect - or rather, everyone's idea is wildly different to everyone else's. I personally never saw the logic of a crop sensor R body, but admit that some of its proponents on this thread and others have been enlightening on the subject. Whatever happens, a lot of people will be disappointed (sorry to sound a pessimistic note).
I could be wrong, but I don't recall any official sources cited. As I'm sure you know, Canon and Nikon seldom definitively declare anything dead.
Good arguments can be made both for and against a high-end APS-C mirrorless body. What no one has access to is the market research that shows if it will be profitable or not.
I'm skeptical, but over the years I've learned not to bet against Craig's rumors, even when they are CR2.
I do agree though that many people seem to be asking for a unicorn, in that they want or even expect that an R7 will be bargain priced like the 7DII.
My guess is that an R7, if it appears, will not be cheap. It might not be as expensive as the R5, but I would not be surprised if Canon launches it at a price that is closer to the R5 than the R6. My reasoning reflects your observation that the market has contracted over the last several years, coupled with the knowledge that the target audience is not particularly price-sensitive -- after all, a $3,000 R7 and a $2,500 100-500 f7 lens are still less expensive than a 500mm f4 EF lens.
I agree there will be lots of complaining if one actually does come out -- either from those who are expecting a bargain or from those who are expecting a high-end body. My guess though, is that it will be the bargain hunters who are disappointed.