I believe if it comes to a point where PAF has to take off from runways, then they might strike back with a final solution, which would not bode well for the entire South Asia. Whether the top brass has the balls to do that is anybody's guess.
The range of SOWs is reduced considerably if they are released at a low height. Probably what makes more sense is to do a low-hi run, release the SOW and scramble. If the range of S-400 is 400 kms, and an aircraft releases its SOW from 400 km, then by the time the incoming SAM covers 400 kms, the aircraft would be well out of range. Depending on relative speeds, there will be a 'buffer zone' within which PAF will be able to shoot and scoot as well.
So, although the PAF has options, if these options were to be utilized today, it would mean significant damage to our infrastructure, and a muted response to India. We need to understand that the cost of losing infrastructure for Pakistan is high. We have less infrastructure, and are financially very limited. Thus, preservation is key until we come out of the current financial crisis.