It's the natural numeric progression of the xxx range. Only the 760 fell (slightly) outside.
TBH I am puzzled at the pricing for the 800D as it is relatively close to the price of the 80D. It's in the 'starter' range but (currency fluctuations aside) it's an expensive starter and quie a big ℅ jump from the 750D and, IMHO, with a few bells and whistles more.
Add the 77D into the mix and I get a feeling that there is some cynivism in Canon's approach. Too soon for the 90D perhaps? I say perhaps as with the release of the new (Mk 5) kit lens, in camera Image Stabilisation (offering some IS to legacy and non-IS lenses), could the next generation of EF-S lenses be built lighter/smaller with less internal electronics, no IS, higher IQ glass with in camera IS taking the load?
I am 90℅ using my M kit and am about to buy the M5 (the M6 looks superb in silver) and I have a 750D for (mainly) video so the new models are not on my want list. The next 18 montha will determine where next for me. The M5 video facility will see my 750D gather dust but in-body IS.......
Steve