Yeah it seems Blitzo's policy of always assuming the less advanced engine will be used until the more advanced engine is clearly in production for a year or two is right bet with PLAAF.
All I can say to the community at large is:
I usually don't like to use memes to convey things in mainline threads --- but that image truly captures the sentiment better than anything else I can write.
My god, since I started PLA watching in the mid 2000s, the amount of times I've seen people get burned (including myself in the early days) by being too optimistic about engines and not having a sufficiently high threshold to actually "verify" an engine is in active use and active production, really boggles my mind.
Nearly two decades now, I've been in this space, and I've seen people get over-optimistic on "XYZ aircraft now powered by domestic engines" (and then inevitably backtrack) based on rumours and/or one-off prototype pictures for:
- J-10A and WS-10
- J-10B and WS-10
- J-10C and WS-10
- JF-17 and WS-13
- Y-20 and WS-20
- J-11B and WS-10 (yes, there was a time when SAC land based Flankers were not safely assumed to always use WS-10s)
- J-15 and WS-10
- J-15T and WS-10
and of course,
- J-20/A/S and WS-15
- J-35/A and WS-19 (and to an extent, WS-13E, WS-21 in some respects)
Save yourselves the grief, and set some higher, verifiable metrics to avoid the awkwardness of having to "backtrack".
J-16 when they started production, and Y-20B production over the last year are good examples of aircraft that we can comfortably say are using domestic engines.
J-16 started using WS-10s from the outset and after 1-2 years of production they never deviated from WS-10, so after that period we could comfortably say they were all WS-10 powered
Y-20B started production about a year or so ago now as well, and being a dedicated new variant of Y-20 without having seen at all with D30s/WS-18, and only being seen WS-20s to this point, means we can probably say safely that it's using WS-20s as standard now.
Once we have something like that for J-20A and WS-15, then feel free to call it.
Until then, I strongly recommend people to take my advice on board.