I disagree. I still expect and hope that the 1Dx III has at least 30 mp. Having shot with the 1D, 5D and R and experienced no downsides with the higher resolution sensors, I would be shocked if Canon opts for fewer mps. I don't know about other sports photographers, but I certainly would like more resolution. In fact, it can be at least as important in sports shooting as in birding. Many sports photographers, myself included, rely on either single focus point or an expanded single point in order to get the player you need to be in focus to actually be in focus. That means cropping. Sports are messy and messy also means cropping. Sometimes radical cropping. Add to that the fact you can be just as distance limited shooting sports as you can with birds, which also means cropping.
The vast majority of sports photographers don't have access to $8,000 lenses. People's opinions on this get skewed because they watch NFL, NBA and Olympics and think that's how most sports photographers shoot.