We'll see if PAF actually ends up going for this. Pakistan isn't known to go for unproven stuff within their limited options if they can avoid it. Case in point, RD-93s for JF and Ukrainian engines for Al-Khalid.
If I'm not wrong (haven't researched this, just going off on intuition) - the higher thrust WS19 was developed to fit within the WS13 framework because the J-35 has to operate from Carriers and the WS13 wasn't offering enough thrust to deliver on the payload requirements of PLAN. But in order to deliver that extra thrust it's likely they made tradeoffs reducing the longevity (& probably reliability) of the engine. The tradeoff might work for PLAN as they probably don't plan on riding their jets as hard as even PLAAF would (let alone PAF or IAF)
But I'm not sure if PAF will be comfortable with that.
If they're smart they'll request RD-93MAs instead.
WS-13/19, F404/414, EJ200, RD-33/93, Kaveri etc are all in the same size and weight class. I don't know how the WS-13 is related to the WS-19, but the WS-19 is a 5th gen engine. It comes with stealth augmentors, IR suppression and TVC, not to mention higher thrust. It should also have a longer lifespan. So at least they are not in the same generation. Or the WS-13 will have to receive the WS-19 upgrades too.
The PAF was wise for selecting the RD-93 for the JF-17 initially, would have been pretty dumb to go for the WS-13 as the only operator. But now the WS-13/19 may be engine choices for both the JF-17 and J-31.
There are some reports about PAF choosing WS-13 for future orders of the JF-17 over the RD-93MA though.
We built the MKI fleet over decades of fine tuning the logistics & sustainment network. Nobody rides (and sustains) the Flankers like we do. Definitely not PLAAF, even with the J-16.
A logistics network for a jet powered by any non-Western engine simply doesn't get better than what IAF has built for the MKI.
I really, REALLY doubt the J-31 can change that.
These things are relative, both to the jets you have and the adversary in question.
So the MKI requires 32 hours of maintenance for every flight hour, and the comparative figure for the F-16 is 17 hours. That's half. The Block 52s could be better. The upgraded Mig-29 requires 11 hours. And Rafale requires 8 hours. So the J-31 could be aiming for this spot.
But relatively, the Gripen E requires just 3 hours and LCA Mk2 could match that. The F-35 requires 5 hours. The Rafale F5 may also match these numbers.
So there's been a shift. Mig-21 needed 50 hours, Mig-27 needed 20 hours and PAF fighters needed 17 hours for the F-16 and 10 hours for the Mirage. Only our Mirages could match theirs. But now our jets would need 3-5 hours of maintenance to their 10+.
And this doesn't even fully consider the life of the airframe and spares. For example, the LCAs may end their service lives with just 1 hot core replacement during MLUs. And Rafale can sustain surge operations for a month. They will fall miserably short there. But the J-31 should provide enough capability to match the M2000's availability, never mind the Mig-29 or MKI.
None of these numbers are concrete, but given the size and weight class of jets, taking into account generation, they can all be classified similar to each other, so the MKI's gonna have to be judged quite a bit more harshly for that, even post MLU.
I'd actually say that by 2025, the MKIs would be the worst jet flying in the subcontinent in terms of sustainability.
We should assume that the J-31 will match the Rafale during the first 4 days of a conflict.
Like I said, it will retain an advantage in look-first/shoot-first thanks to IWBs but I doubt it's better as a platform to sustain.
I'd bet that over a protracted period, even the Tejas can put up way more sorties than the J-31 can. And that's before we take into consideration any additional complications introduced by maintaining the LO airframe.
It's likely PAF knows this and likely won't expect the J-31 to successfully operate for long beyond the opening stages of the conflict, as their airbases are all well within our reach anyway. But it's likely to give them an advantage early on - and that's probably why they're going for it.
All upcoming Indian jets will produce more sorties than the J-31. So this is what I'm getting at. The J-31 will sustain ops better than the Mig-29 and MKI, but PAF giving up Western jets means they give up on Western advantages of even higher sustainability.
Anyway, by the time the J-31s arrive, the Mig-29s will be gone, so who cares? But the jet will most definitely provide more bang for the buck than the MKI. And if we screw up our modernization, then we are in trouble.
On the naval front, I agree. Though a lot of it comes down to TEDBF flying off STOBAR going up against a CAT-launched J-35.
We need supersonic bombers carrying long range AShMs before the Chinese get 3-4 flattops.
Thankfully naval battles are mostly long range now.