If anything I'd say just the reverse is true of the 1DX and 5D mk3, there actually cameras that do step on each others toes far more than had been expected with the latters improved AF and FPS. The disapointement for many has been that we havent thus far seen a FF DSLR that offers greater resolution.
Except that one has twice the fps of the other, an even better AF system and not to forget gigabit ethernet.
Is that a product of Canon crippling a product to protect the market of another though? the 5D mk3 offers a better combination of AF and FPS than any other FF DSLR in the same price/size range has done. The 1D line on the other hand has remained competitive by moving to FF and upping its FPS to 12 rather than depending on lower level bodies being crippled.
Canon's problem seems to be that Nikon/Sony are targeting the high resolution market and they have so far not released a rival product.