Quite unlikely to be WS-13 since that was never intended to go into any PLAAF fighters and only quickly put together to pressure Russia into selling RD-93 engines to the Pakistani JF-17 back in the 2000s. The WS-13 I don't think has ever completed development or been properly funded since RD-93 supplies to Pakistan were inked.
A WS-19 (mid thrust class) engine for J-xy is anticipated. We know it isn't using the WS-10 or WS-15 and it sure isn't using the old WS-13. J-xy is anticipated but unless the engine for the 5th gen fighter is already long completed, is there really any chance China would approve it for use on the JF-17? It'll probably require extensive changes to block 3 which should be completed. The timelines simply do not work out. Therefore it is likely the engine if the rumour is true, is simply a new RD-93 variant.
If J-xy's WS-19 is ready before J-xy, this is both unlikely and it's also unlikely the JF-17 will feature this engine first particularly as unproven engine for a single engined fighter
WS-13's sole purpose was to ensure JF-17 has an engine no matter if Russia decides not to supply RD-93. Beyond this purpose, it has received no funding or completion of development that we know of. No PLAAF fighter is designed for the WS-13 engine.
Leaving only RD-93 new variant which was rumoured anyway. This also means no need for extensive redesign of JF-17 to integrate with WS-19 even if that engine is available now and considered by both China and Pakistan to be mature enough for single engine fighter. Completely impossible.