I agree with your calculations - at least close enough for a good estimate. Currently CF cards max out at 100 mbs - and that is a recent enhancement. There is a practical limit of speed on CF cards and we are approaching that limit. XQD Cards promise much faster speeds.
The one thing we don't know is the maximum processor speed in the camera. In practice, the camera will write at the lesser of the maximum processor speed or the write speed of the card. And anything that slows down the processing of images - such as image processing or lossless compression - can further reduce the camera speed regardless of the CF card write speed.