Platforms like the J-10C and the J-16 are considered 4+ generation fighters. And the J-20 is even 5th generation. And will no doubt do better than the older 4th generation fighters. However removing them from the frontline will take a long time as China still has large numbers of older J-7, J-8 and Q-5's in service.
I don't agree that China should prioritize the J-16 and the J-20 over the J-10C. The J-10C is much cheaper to buy and operate than the J-16. So having these fighters in larger numbers will mean more bang for the buck.
I think J-16 and J-20 should be prioritised over J-10C. Remember J-10 production presumably comes at the expense of J-20.
Look at the likely scenarios.
Additional short-range non-stealthy J-10 won't make any difference with regard to China's next door neighbours ref: India, Vietnam, Taiwan or Korea.
But additional long-range stealthy J-20 and J-16 will make a huge difference to the countries above, PLUS the South China Sea, East China Sea, Japan and to the 2nd island chain.
And for future J-10, it does look like it would benefit from conformal fuel tanks which will increase range and possibly reduce aerodynamic drag as well.