OK, my two penneth worth on this.
The 5D2 has no bearing on the 1DX market i can assure you. Having played with it, the price is such that no one is going to buy this over a 5D2. I love the high ISO, it really is wicked. I love the AF system - really, it is the answer to my prayers for sure. I love the ergonomics of the body and the new placement of buttons and extra joystick
but - and it's a BIG but
The 1DX is over twice the price of a 5D2, and we know what happened to the last camera Canon made with a 21mp FF sensor that was over twice the price of a 5D2 - and this one is 3mp less!
However, press, wedding, wildlife, sports, action photographers whose livings depend on getting "that" picture will love it. Really. I would love it, it really felt comfortable in my hands - but not at that price.
A 5D3 with specs as i've mentioned else where on this site would appeal to the old 1Ds brigade who do not want high frame rate, 61 focus points or 204k ISO (though i'm sure an increase by a stop or 2 would be welcome). Just update that awful focus system, even to 9 full cross hairs, and up the sensor MP and Canon would be onto another winner. Oh, and add in that Gigabit network socket - no faster way of transferring such large file sizes or working tethered so easily. Hooked to an iPad? Hell it could be hooked to a 52" LCD screen which would really impress the clients in the studio!
To summarise - the 5D series will be the new 1Ds series. The 1Ds is dead. Those previous owners have spoken with their wallets, and made Canon an absolute fortune - why would Canon abandon that market?