We’re told that the Canon EOS 7D Mark III, which will be Canon’s first APS-C 4K camera, will have a slight crop when shooting in 4K.
As for frame rates, do not expect anything more than 30fps in 4K, and 60fps in 1080P.
There has been no mention of whether or not this camera will get a CFast slot. The EOS-1D X Mark II does, while the EOS 5D Mark IV does not. We’d like to see the EOS 7D Mark III get a CFast slot along with an SD slot.
We don’t yet have a solid announcement timeframe for the 7D Mark III, we hope to solve that riddle soon.