If Flanker airframe production continues at about 40? per year, then in 2030, that would be about 500-600 J-16 in total.
And you're talking about teaming J-16s with J-20s.
The J-16s would be launching PL-17 missiles at long range.
You wouldn't want the J-16s to launch PL-15/16s, because that would require them to get closer and make them too vulnerable, as J-16s aren't stealthy.
So we're only looking at the J-16s launching a single long-range volley of PL-17, before the J-20 and J-35 close in with PL-15/16s.
If each J-16 can launch 4 PL-17 missiles, then 500 J-16 should be more than enough.
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As for countering larger numbers of F-35 stealth fighters, the best method is to target the small number of airbases available and destroy those F-35s on the ground.