A 1D X mark 2 replacement will be out before July 2020.
It will have dual CFast card slots
That's an exceedingly modest prediction. Can't you do better than that!
It bugs me that there wasn't even a modest attempt to update the camera. For example, why it would default to CF after having removed/inserted cards when the best performance is with CFast (CF=1, CFAST=2). I tried to get them to modify photo review so you coud go back over a sequence without first having to hit the shutter (you otherwise can only view the last shot). I somehow don't think the 1DX2 is very high prioritity and doubt if an new version will have much added.