I can't help think Canon heard about Nikon's D4 and decided to go in early and announce their camera far earlier than were originally going to do so.
This interview (translation) is with the 1D X engineers from Japan. They admit to their consideration of Nikon, Olympics, and pro customers.
"... Timing of the 1D X announcement was to quell questions about the 1Ds replacement and to warn pros before the Olympics, and in consideration of Nikon, which they consider to be their biggest competitor when it comes to pros..."