Well this is a quote from Canon's press release for the 1DX:
"As the new leader in Canon’s arsenal of professional DSLRs, the EOS-1D X will be a high-speed multimedia juggernaut replacing both the EOS-1Ds Mark III and EOS-1D Mark IV models in Canon’s lineup."
Need any more be said?
one thing that could be said is that an official press release saying that an 18 replaces a 16 and a 21 doesn't necessarily change the opinions of, or how these respective cameras are viewed, by those who use them professionally.
Another thing that could be said is that press releases like this are designed to sell products and to optimally frame the company's acheivements to date versus the compromises they have made.
Still another thing that could be said is that the release is absent any meaningful reference to how Canons long standing tradition or legacy/whatever intends to address those distance constrained situations where getting more pixels on the image is paramount.