A 1DX II where the only change is to a crop sensor? Will never happen without major deliberate nerfing/limitation of that rig, and I'll tell you why.
For a long time, the 1D brand had to have features that the 5D brand's users would drool for. Let's take spot metering at any AF point or perhaps a dedicated AF/metering module, for example. Were they to put this functionality into a new 5D model, it could (in some small way) threaten 1D sales and the premium that it asks for.
Now extend this analogy to the 7D brand. For this camp of shooters, the killer apps / features would be an integral grip, the next-gen of tracking AF, expanded teleconverter use and 16 fps. Were Canon to offer this rig even at the same price as the 1DX II, they'd lose money on people not needing as much reach, which would hurt their supertele lens sales.
Now, would they stuff a crop sensor into 1DX II body and deliberately nerf it, perhaps capping at 10-12 fps, sticking the current 7D2 AF module in there, etc.? Possibly, sure, but I'd peg it as unlikely.
But I still think there is a far larger market (and money to be made) by Canon putting a high res / low fps setup into a 1D body a la the old 1Ds line. Right now prior 1Ds owners have a choice of a 1D feature set or a 50 MP sensor. Canon's leaving a ton of money on the table with each studio or landscape photographer buying a 5DS instead of a pricier 1D rig with that same sensor in it.
- A