There is a reason why the US is stocking up on F15s and lots of F16s are still in service.  In a war of attrition, numbers and cost matter.  Why should China decommision J10s so they can have more high tech stealth fighters?  Sure, it is nice to have stealth fighters if they can produce enough of them, but then again to have lots of 4th gens is crucial.  At least they are cheaper and easier to produce.  Robust too. 

At  this moment, Stealth is overrated in a real war. With their limited numbers, they are good for certain roles.  A large number of 4th gens are even more crucial.

Maybe in a couple of decades, all figher planes can have stealth capabilities.  Not now..  

Do you agree with the original poster to get rid of J10s for more stealth fighters?  Say, hundreds of J35s with domestic engines? Will that be a difference maker?