It might be true the Su-33 is old and will be replaced by MiG-29Ks, however the Su-33 were updated a few years ago, the Su-33 China has is a late 1980s aircraft, because J-15 is a a upgraded Su-33 . however the Russian Su-33 will be replaced today by more modern MiG-29Ks with 10 tonnes of Thrust engines giving the MiG-29K 20 tonnes of thrust at take off and new avionics, so comparing Su-33 with J-15 does not represent a realistic measure, since Su-33 has been barely upgraded
The purpose of that article is not about comparison of J-15 with Russian Su-33. It's about shutting up those amateur who think J-15 is copy of Su-33. If J-15 is copy, it shall copy completely everything from avionics , system and capabilities to qualify as copy, just like how Soviet did it for Tu-4. I heard some of the dent was even copy as Stalin instructed to copy Boeing B-29 exactly everything.
Clearly with a different radar, avionics and combat capabilites. J-15 do not qualify as copy. Beside the outside frame looks like Su-33, everything internal of J-15 is different.