Chinese Su-35 Purchase Suggests Lack of Confidence in Local Defense Industry

The announcement on 19 November that China would buy 24 Sukhoi Su-35 combat aircraft is being viewed as a clear signal that Beijing is still dependent on Russian-made hardware for its primary defence requirements.

The contract came after years of negotiations - and only after interventions by what has been described as "the highest levels within the Kremlin".

link.

My bet the J-20 is delayed.  Given they just rolled out another prototype, the 8th, I'd say that's the case.