I'd imagine the transition would be body only for sports photogs at first. It isn't the $50k-$80k cataclysm you suggest. Lenses will be replaced just as they would have if the mount had stayed EF. So, in my opinion, things didn't get exponentially more expensive. EF lenses work on the RF bodies.In my opinion this camera is not for someone currently shooting with a 1DX 1DXMKII or 1DXMKIII as a professional to transition your kit from EF to RF at a $50K to $80K+ investment.
1. The loss of OVF
2. Two Different Format Cards
3. No significant jump in resolution
4. Transition to RF Glass
These four factors will make us wait until the R1 is released. Also 30fps is no inducement we know all that is required is 15fps RAW for stills for any sport.
This does leave one to wonder if Canon will double the resolution of the 1DXMKIII for the R1. We are seeing people shoot sports with the Fuji GFX100s and the work is amazing, stunning, beautiful, sharp, crisp with exceptional detail and resolution.