I don't think we can dismiss the possibility of China purchasing Ka-50/52 just because they have other projects on the way. As we've seen with Su-30, Su-35, 636M, 051C and Sov class purchases, they are willing to place small purchases to gain immediate ability even if that means having a small fleet of aircraft or ships that don't use domestic system that they need to maintain. They value the need to train their forces sooner over waiting for better domestic options to come along.
It's quite interesting to me that they have not tried a naval version of Z-10s. Maybe they don't think it's well suited onboard amphibious ships. I see the main domestic options for 075 to be the various Z-8/18 versions and Z-20s. It's quite possible an armed version of Z-20 would work here. Although, I do think the long term play here is a larger dedicated 10-ton class attack helo similar to Ka-52. I'm under the impression that program is under development, but might not ready for service until 2025 or later. The question is whether or not PLAN desires a dedicated 10 ton attack helicopter in the next few years. If it does, then Ka-52 is very logical. It gives them time to train with it on Type 075. They can discover what works for them and doesn't. All of that would improve their own attack helicopter program. If they don't think a dedicated 10 ton attack helicopter is needed, then Z-8/18/20s are probably sufficient. The deck is long enough for UCAVs to take over some of that roles also.