I think there was a news around mid this year suggested the newest batch of airforce junior pilot was trained in CJ-6, JL-10 then directly J-10, so yeah, don't know how long those J-7 could still be used even as training
The PLA is frugal. They’ll fly them until the lifespan has been exhausted. Once all the J-7s are retired you’ll see the older J-10s and flankers filling in for them.