Well, the crown jewel of S-400 is the 400km range 40N6E missile. Without 40N6E, the S-400 is at best comparable to the HQ-9P (most probably the HQ-9C) with publicly stated interception range of 260km (ofcourse 100+ km as per PA). The 40N6E has only been up until recently arming the Russian military after its successful trials in 2018. So it itself could be debated if India has received the 40N6E yet, and if not, india has barely just gone back to a status quo with our HQ-9Ps already operational.
Secondly, in the worst case, even if India has received the 40N6E, the engagement in our airspace (at any ranges let alone the farthest) would be a major escalation on India's part and statically positioned and assuming the system has been deployed within 140 kms of border (which otherwise would eat into its maximum range itself) , the PAF SOWs, PA Fatah-1 MLRS (140km precision targetting) or ALCMs/LACMs could take the engaging batteries out. So in a sense, not doubting about the lethality of the S-400, it would be an escalation which would be responded to and thus doesn't change the status quo currently in order.
And lastly, we must also not forget that with the 91N6E radar of S-400, although India could peep 600km deep into our airspace, it essentially doesn't change anything for India since it was already using the Israeli Swordfish radar with similar or even higher detection ranges.
I personally think that PA AND PAF should also give serious thoughts to adding land-based radar electronic warfare systems like Koral (effective range 150 kms) or similar systems from China and Turkey, given them being end users of the system, must be better positioned to create signal countermeasures, which would add a further layer to countering the S-400.
With all being said, with the introduction of S-400 in the mix, the strategic planners have their hand full in taking care of the system which needs some intricate attention. Shaheen exercises would be getting even more purposeful in the future for sure.
)
