PAF cannot afford that luxury of swapping engines mid-service - best to wait - China is close to getting the new engines ready for prime time. Right now - the 271 BVR equipped fighters with AEW&C and the new IADS are more than enough to hold off the IAF.
I agree, better to wait for the engines. This applies to both the J-31 as well as the KAAN. For us, the top priorities, for the next 5 years, have to be our political issues and economy.
If China is right around the corner from ramping up production of J-31/35 and J-20s, once it retires it’s J-7s, J-8s, and JH-7s, it will move on to early Flankers and J-10s. Therefore, PAF should look to see if it can ask China to sell its early J-10s. With refurbishment and upgrade to cover the retirement of F-7s and Mirages. We already have built up the infrastructure for the 25 J-10CP. Picking up an additional 65-75 older J-10s would also allow J-31 procurement to be pushed back, beyond 2030, and until China has met its needs and perfected the design, much like how the PAF operates the J-10CP, probably the most advanced version of the J-10 that will be fielded, as China loves on to 5th gen fighters.
Should relations improve with the US, such that the PAF can get at least the Turkish Ozgur upgrade, that will also help the PAF buy even more enough time. Ozgur might be an even better upgrade then an American upgrade, because the PAF F-16s would get a more reliable and more capable uninterrupted supply of munitions from Turkey then the US.
Assuming even with attrition and retirement of older airframes, the PAF could have a very capable
all 4th gen fleet in 2030 of 20 full strength squadrons; enough to hold back an IAF of under 30 squadrons.
The next 5 years have to be about the economy, so 3-4 squadrons each of the J-31 and KAAN can be procured in the 2030s and 2040s, and the PAF can keep its edge over the IAF.