Frankly speaking, I wouldn't be surprised if there is indeed a sister ship to CV-18 Fujian (let's call it 003A CV) coming out of Jiangnan which still retains the COSAS propulsion system from her elder twin even if the 003A CV is eventually launched (if not also commissioned) later than the 004 CVN from Dalian.
In my view, this potential new development could also be seen as something of an insurance policy by the PLAN higher-ups. That is, they might be more keen to ensure that their carrier fleet retains sufficient number of carriers for use, just in case China's first nuclear-powered 004 CVN faced difficulties and challenges at any points of its development, construction and service processes.
And for those who are saying that three carriers are sufficient for China's current needs - A reminder that CV-17 Shandong still can't operate J-35s today (yes, that's a fact), unlike her post-MLU-ed twin i.e. CV-16 Liaoning. Shandong's present daily sortie rates are also worse than post-MLU-ed Liaoning's despite being a much newer/younger ship, so there's that.
Of course, this is not to say that I'm against IEPS with gas turbine engines and diesel engines - If anything, I'd seriously prefer this type of propulsion system to succeed the Fujian (or her class) as the conventional branch of the PLAN's CV fleet (if such "thing" does exist).
Unlike what some in this forum had argued - China going forward does have the ability to equip her warships with more powerful gas turbine engines/generators (40MW-class, 50MW-class etc) and diesel engines/generators (6MW-class, 8MW-class etc) than what she had before. This is yet to consider all the advantages of GTG+DG IEPS over COSAS, including-but-not-limited to:
1. Saving a lot of internal hull spaces for the same overall hull volume;
2. Greater power density;
3. Greater power generation capability;
4. Superior flexibility and operational flexibility;
5. Superior fuel consumption and fuel efficiency; and
6. Optimizing fleetwide fuel logistics.
Sure, having a twin island superstructure like those on the LHD-51 Sichuan can eat into a few parking spaces on the flight and hangar decks, but the all-round upgrades in the performances and capabilities of the carrier can never be understated. In fact, SOYO did make a couple detailed posts on Weibo explaining and justifying on this idea before.
In fact, do countries elsewhere even looking forward to large-sized combatant warship projects today and into the future that are powered by conventionally-fueled boilers + steam turbine engines anymore?
In the meantime, all the above paragraphs on GTG+DG IEPS squarely hinge on the notion that the PLAN will pursue conventionally-powered CVs post-Fujian (or post-Fujian-family). If this is not the case, then the entire notion and discussion of post-Fujian/Fujian-family developments will become rather moot.
All-in-all, I don't see the need for anyone here in this forum to go "I will die on this hill" with regards to this particular debate, really.