Some Chinese military KOL thought it's rumor, the navy version of Ka52 is not ready yet, the ocean radar is tested on it yet. Even if China orders some, it's not a question, the production of Z20, WZ10, WZ9, Z8 is full speed now, but still not enough.
China bought Su35 only with 24, after that didn't order for 5 yrs, maybe it's good for PLAAF and PAF treat it as enchenced version of Su30MKI.
S400 is a long range missile, good to have it as one of many options, we buy first, it also blocks India's purchase somehow, or we also knows the specification of Indian version would transfer to PAF.
Oil and Weapon are the only two stuff Russia would balance the trade with China, it's also a political issue.