+1 on 5D3 getting the red.
I don't think Canon will 'premiumize' this and withhold it from the 5D3. It's a clear miss on a pro body, and people will clearly not pay 2x the 5D3 price to get red AF points. I'm confident this will be rolled out to 5D3 as well.
My only fear is that they haven't released it at the same time because the difference in the extra processor for 1DX allows for recalculating exposures with the red AF point. Hoping someone with more technical knowledge can allay my fears.
I don't think that's an issue as the metering still takes place with the AF points off:
To preserve exposure-metering accuracy, illumination is intermittent, not continuous.
5D3, 5D2, Sony α6000, G16 | SY14 f/2.8, Ʃ20 f/1.8, 24 f/2.8, 35 f/2, Ʃ35 f/1.4A, 50 f/1.8 I, Ʃ50 f/1.4 EX, 100L Macro, 17-40L, 24-105L, 70-200 f/2.8L IS II, 1.4x II, 2.0x III, 70-300L | E-mount: SY12 f/2, 30 f/2.8 EX DN, 16-70 ZA OSS, 55-210 OSS, Metabones SB | FT-QL, AE-1P | FD(n) & FL lenses