A couple observations:
1) Canon's high-end glass releases have slowed over the years. I do think they're putting out the best they've ever put out, but they're not releasing many variations versus 5 years ago. We may find that this was partly due to them holding off on releasing the R lenses until the body was ready, and perhaps they'll make up some ground, but current reports are that they won't release any new EF lenses in this entire year. So if I were to pick up a 7D2 replacement, I'd want it to be in R, as I'll know the new glass investments will matter for the long-term. Meanwhile, I can use my nice glass with the adapter with very little downside, and even some upsides. If they release the 7D2 replacement in EF, I don't anticipate I'll bite.
2) What seems like Canon's primary tech weakness is throughput and processing speed. If this isn't fixed, it may well mean we'll get another EF-mount 7D. The 7D2 was used as a platform to develop a few new technologies that were later adapted into the 5 and 1 series, but I wouldn't expect that precedent to mean much. Most times Canon when uses one model as a major tech introduction platform, the next revision winds up being more incremental. Think 5D2 or 1DX or 6D. People who thought the 5D2 meant the 5D3 was going to push the video envelope were disappointed, as were people looking for a new record for price/low light performance with the new version of the 6 series. Canon is perfectly capable of putting out a 7D3 in EF with a very slight bump in sensor performance, no increase in FPS and a few new interface features, and calling it a 7D2 successor *particularly* because it is consolidating it with lower-end lines. My hopes are not hight, but as is often the case, I hope to be wrong.
3) Canon's crop naming schemes seem so irrational as to be the product of individual brand manager's choice, trying to optimize sales for a single camera, rather than creating an orderly set of camera line names. I think you can dismiss names as meaningless for accurate predictions, but it might be safer to guess there will be some consolidation among the crop lines. Since may people have a tough choice between an 80D and a 7D2, it sort of makes sense to combine them. Throwing the 77D (winner for oddest Canon name) in wouldn't put too many people's noses out of joint.