Operating cost per hour of F-16V is 7000 $$$ so I assume that J10C has also same Operating cost of F-16V, whereas if we can assume that J-20 is comparable to F22 and F35 its Operating cost per hour in between 42,000 to 85,000 $$$ which is the Operating costs of F22/F35 respectively and I also searched the Operating cost per hour of J11 which is comparable to F-15 both have similar Operating cost per hour of 24,000 $$$, so your theory is ridiculous and funny that you have hundreds of J-20 so you don't need J10C for air superiority,
USA also have more than 1000+ F35 that doesn't means rest of USAF fleet is become useless lol