I preface this by saying I am not a professional and have never used an APS-H camera before. And I'm sure Canon has had many discussions about the APS-H form factor cost/benefit analysis. But here is my two cents for what it's worth (about two cents).
I can see a continued market for an APS-H form factor in a weather sealed pro/semi pro level body that can autofocus to f8. The intended target for such a camera could be wildlife photographers. Wait... Canon has such a camera now in the 1D IV and have chosen to eliminate it with the 1D X! They must have a reason behind this move. Will the 1D X have better image quality than the 1D IV? Almost certainly. BUT, being full frame and "only" 18mp, it won't have the extra reach due to pixel density many who use super telephoto lenses desire.
Seeing no currently announced camera in Canon's lineup will autofocus at f8, my uninformed guess is we'll see a camera designed for the wildlife photographer so they can use their massive (and very expensive) 500 and 600mm f/4 lenses with a 2x teleconverter and maintain autofocus.
Maybe a 7d Mk II will autofocus at f8 and will become the go to body for wildlife photographers. Or maybe not. APS-H seems to be the compromize between 1.6 crop reach and ff image quality.
Again, my two uninformed cents.