Canon has been behind Nikon/Sony in DR for several years, and yet they have soundly outsold both Nikon and Sony during that time. Conclusion? DR is irrelevant to camera sales, therefore DR is irrelevant to profit, therefore DR is irrelevant.
The 5DII way, way outsold the D700 despite the D700's better DR. If the D800 way outsells the 5DIII, why on earth would Canon think DR had anything to do with it? The only logical couclusion for Canon would be that the D800 had outsold the 5DIII because of 36 MP vs. 22 MP, and Canon's answer will be more MP, not wider DR (DR may, in fact, be reduced with the higher MP, but as stated above, Canon already has evidence to show that DR is irrelevant).