A small to medium sized buy of Ka-52s and Ka-52Ks is probably one of the few purchases from Russia (that they're willing to sell) that would be useful to the PLA now and into the future, as that list is dwindling by the year.
As a 10-11 ton MTOW attack helicopter, the Ka-52 family are in a different weight class to the 6-7 ton Z-10s (let alone Z-19s), and what that means in terms of weapons load, sensor size, and armour is quite significant.
Developing a 10 ton MTOW attack helicopter is definitely within the Chinese aerospace industry's capabilities at present, and they can adopt much of the Z-20's subsystems (engines, rotors, transmission, if not elements of the flight control system) to an attack helicopter derivative not dissimilar from the UH-1 to AH-1 evolution, and many of the avionics, weapons systems and datalinks would likely be iterative from existing attack and scout helicopters. But... that will still take time to develop, test, verify, and produce.
A purchase of a few dozen Ka-52s and Ka-52Ks basically gives a relatively quick boost to the heavy attack helicopter capabilities of the PLA, and would probably be most relevant for a Taiwan contingency, to be frank, where payload and survivability of the attack helicopters would be of greatest concern (as far as the PLA's major strategic directions where a heavy attack helicopter would be most relevant in).
Needless to say, if such a purchase does go ahead, I expect the PLA to insist that at least domestic weapons systems and datalinks are integrated, if not domestic sensors and cockpit systems as well.