Not a great comparison.
15 years ago the scale of J-11B likely wouldn't have been expected, and certainly J-16 wasn't a thing back then.
And for the PLA, excessively large scale procurement of the smaller J-10 likely would not have been a very good idea.
In fact, we combine the number of domestically produced 4+ and 4.5 gen fighters overall (J-10 variants and SAC Flanker variants) from 15 years ago to now, you'd probably get to about the number of J-10s that would've been projected from back then.
That said, it's very possible that J-20 production rates may sustain at the current projected rate for too many years.
However, your comparison is flawed because the excitement about J-10 production rates from 15 years ago was made on the basis of simply "producing a domestic fighter" (of which only J-10 was available at the time), rather than "producing the best mixture of domestic fighters that will be available in the near future" (which they understandably wouldn't have been able to foresee back then).
The difference of course is that J-20 is a proper heavyweight fighter with the kind of range and persistence that the PLA actually needs in large numbers as a mainstay fighter, and while the J-10 is an excellent fighter and offers greater affordability and lower logistics and maintenance needs, it is notably far smaller compared to its Flanker equivalents with correspondingly greater range.
