I am not saying that that alignment makes a match, at each level in my line up the canon body would be better than the Nikon. Clearly the 5DMK3 is better than the D600, but the D600 is much closer to the 5DmK3 than the 6D, it is about 90% of the camera depending on needs (if you need pro AF then the difference is much more important between the 2).
It is just a fact that Canon doesn't offer a true high res camera and there is a large demand for a new one. 1DsMK3 and 5dMKII owners that purchased their cameras in part due to the high resolution sensor and actively need to the resolution for landscape/wildlife/studio etc have absolutely zero upgrade options with Canon at the moment. 1Dsmkiii owners have gone from, a near top of the line 21MP sensor down to an 18MP sensor. The imminent existence of a new high res Canon body is a certainty or Canon will loose massive share. This upcoming Canon 3D could be a 1D style full pro body etc.
If Canon don't release a high res body then they will loose a lot of the top end DSLR market share - nature togs are already swapping out for a Nikon setup because they have given up waiting on Canon.
I expect the rumours of the 3D go back a long time and get muddied because it was not clear what camera the 5DMKIII would be. At one time there was high exceptions of the 5DMKIII being a 38-46MP camera, with the 1DX released then people were thinking it would be the same 18MP sensor- no one expected Canon to simply tweak the 5DMKII sensor some more and play conservative with the pixels which has never been Canon's strategy.
To reiterate, I am not claiming that with my line up the bodies are in any way equivalent but to me from a a feature perspective that line up makes for a closer more balanced table. People always try to line up Nikon and Canon bodies and this is rarely a good idea (typically one of the bodies fits neatly between 2 bodies of the other manufacturer, only the top and bottom can be compared) and I have told people not to do it before myself, yet I am guilty of trying to make an alignment myself.