If it ends up being an action-oriented crop version of the 5DIII, I might buy both of them. However, if it has some innovative features that the 5DIII lacks (dual pixel, hybrid viewfinder, other video stuff), I might wait for those to move to the 5D series and buy both at that time.
I've said it before - I shoot with a 5D and a 20D, and I love that they are so similar in UI.
Given that the 7D and above are more workhorses than a show ponies, I'd imagine we would not see a hybrid viewfinder, tilty-swiveling screen or touchscreen in this market segment for some time. I do not
expect to see them on the 7D2. I think all of those things are potential value-add for photogs, but Canon will certainly test out their value, appeal and reliability on lower trimlines like the XXD or Rebels first (rationale: fewer pros in this segment that might be alienated by a 'dud' of a feature).
Keep in mind, the current 7D and 5D3 already share a bit of 'feel' about them -- I have a 5D3 and my friend has a 7D, and they feel about the same in the hand, use the same batteries, etc. And though my 5D3 has more AF points, the Servo AF tuning system in my 5D3 came straight from his 7D.
So I see the 7D and 5D lines helping each other along on ergonomics, menu system, etc. In the lesser-discussed-things, one might expect the 7D2 to now get some 5D3 love in the following features:
- LCD zoom button straight to 1:1 for pixel peeping for focus confirmation like with the 5D3*
- Similar AF clusters and selection process (on LCD or through the VF) as the 5D3
- Lockable mode dial (if there is one...)
- 5D3's sockets for video/audio options
(Not owning a 7D, I don't know if current 7D users already got this in the massive firmware upgrade from some time ago.)
Dual-pixel and 'other video stuff', however, I would
expect. With it's reach and build quality, it could become the wildlife videographer's rig of choice.