Not that I would know, but my guess is that CX/KA will not hog a terminal to themselves - because HKG is an important OW hub, it will likely use the same terminal as all the other OW airlines. The other terminal will be for HX/UO and all the other airlines.

But I wonder what would happen to the CA codeshare flights to Beijing...

Also, would this mean bigger expansion for HX? I hope not, really dislike that airline, but it is more or less guaranteed right? Seeing that they are probably backed somewhat by the Chinese government.