I am not really an authority here, however the 7D, being a new line of cameras, hasn't really established a replacement schedule. On top of that, the 7D is still a superb camera, and probably will be for some time to come, so I personally don't see a replacement coming for some time.
I think its at the limit of lens resolving power with 18mp, so there likely wouldn't be an increase in resolution. You might be able to improve ISO performance, but I doubt that alone would really be grounds for an upgrade. Canon, along with many of the other manufacturers, has been hit fairly hard with the recent chain of east pacific disasters. That has hurt their manufacturing capacity. Additionally, Canon is currently gearing up 1DX manufacturing, is apparently working on the 5D III, and is also cranking out new lenses. Thats nothing to speak of their new C-line of cinematic cameras and new EF-mount C lenses. With all of that, I'm not sure there is any logical reason to design and release a new 7D II right now, or within the next year or two.
Hope that helps.