Whereas canon's had the split of:
1D: high speed
1Ds, highres, high(er) DR, low(er) noise (than the 1D, although they don't really have a low-MP high-iso D3s direct-competitor)
for 10 years, and now it's combined into the 1DX, high-speed and (allegedly) higher DR and lower noise in one. But they're still going to lose out on the high MP market, or they're banking that 18mp is "high enough".
I still don't believe a D800 is 36MP, because it would be around $3-4k, I reckon it's either a D4X or a new model between the D700/D3 lines, so D453434000 by their naming conventions.
In the red corner, I wouldn't be surprised at a 30+MP studio-version, less-rugged, less-AF, low-fps 2/3/4D @ $3-3.5k, which will keep the 5D3 for the 1DX-sensor in a lower-specced body...