To summarize:
1. J-15s are being inducted and will give the PN a major boost in terms of protecting SLOCs effectively, giving a far superior air defense umbrella for PN ships to operate under.
2. J-15s will also be a threat to IAF and IN Southern coast including Mumbai. Just the threat of this will cause IAF to pull assets away from Pak borders, using them defensively rather than offensively against Pakistan.
3. J-15s are naval platforms, meaning they will have superior lifespan operating over sea.
4. J-15s will come with a host of weapons such as PL-15, hypersonic ASMs, and may even integrate Pak munitions.
5. EW variant of J-15 will also be a major capability upgrade, giving a Growler like capability that will degrade IAF offensive and defensive capabilities.
6. I am initially estimating (and I can be wrong, this is my speculation) that there will be at least 1 squadron in the South for naval duties, and at least a flight each in Northern Command and Central command. (A flight is 4 aircraft).
7. J-15s in North and Central will likely be more EW focused. They can also be utilized for their powerful AESA radars which will burn through Indian EW and make countering Rafales easier.
8. JF-17, Rafales, J-31, J-15 all have sensor fusion, sophisticated EW and AESA radars. The difference is in the size and capability of those.
9. J-15s would possibly have the biggest, most powerful AESA radar in any combat aircraft in South Asia (or possibly in the world). And considerable capacity for EW that a larger platform allows.
10. In terms of induction, I believe the Rafale and J-15 will both see rapid induction, faster than usual for a new platform. Here the JF-17 Block 3 has the biggest advantage as they are not a new platform in the same sense, and will see the most rapid deployment.
11. I believe (and I can be wrong), PAC Kamra has the capacity for 25 aircraft per year and work on Block 3 started in November, 2019. This means that by November 2020, PAF should have 25 aircraft being inducted. COVID may slow them down, but this will be compensated because of the increased urgency.