I guess getting rid of the J10B entirely makes sense for the PLAAF to simplify the logistics side of things.
For Indonesia, I heard that their preference for second hand is more for internal politics where it is widely assumed/believed by politicians and the general public that second hand means a fantastic deal, even when it’s not the case. So it’s much easier to get approval for second hand as opposed to brand new, and there is less risk of public backlash at ‘wasteful’ arms purchases.
I think the biggest question make for me is whether they will do a radar and avionics upgrade before the sale and transfer of the J10B. Normally you would expect a refurbishment, but to bring them back to peak performance levels and make up for degraded performance from normal usage and wear and tear, and also to tweak the radar so it’s not behaving exactly like in service assets for opsec. But in this instance, both sides might be ok without a major overhauls.
For Indonesia, they get the benefits of lower cost, earlier availability, and the assurance that they are not getting a monkey version, with the added bragging rights of saying they are literally operating 100% PLAAF version of the J10.
For China, they might just not be bothered about given Indonesia their original version of the J10B since that’s such a niche type that will be gone from PLAAF inventories anyways since they will be selling the entire fleet.