Add another data point to your list of unknowns that would give us a clear signal:
- It has the "sticky" subject tracking and/or AI facial recognition database that the 1Dx III has.
Lots of wishful thinking on my part and the "6" naming scheme may hold.
It is probably too soon for an action oriented R body, but it is fun to think about.
I'd envision a body with the 1Dx III sensor, "sticky" tracking of subjects like the 1Dx III, AI facial recognition but with a smaller database, no integrated grip, dual SD II cards, slightly smaller buffer, faster and more accurate AF Servo (This is important because, when you use the R and select autofocus points with your thumb on the touchscreen you don't have a second thumb to also activate back button autofocus. Either the servo needs to respond almost instantly for action shots or you need a combination thumb pad like on the 1Dx III).
Slower frame rate, slower memory cards, smaller buffer, lack of integrated grip would provide the needed differentiation from the 1Dx III and would be very similar to the differentiation that existed between the 1Dx and the 7DII (aside from the smaller sensor).
The superzoom lens does make me think they will be coming out with an action oriented body.