Man the PAF is doing a marvelous job of defending our airspace and its planning is absolutely brilliant, so none of us should be worried, except for the Hindustanis of course.
Once the JF-17 is equipped with the AESA radars and BVR missiles, it can effectively defend Pakistani airspace with the radar coverage provided by our very capable AWACS fleet. We should remember that heavy fighters such as the SU-30 and Rafales are designed for the defense of huge areas without support from other resources. But that makes them inherently less suitable for short range work. I read somewhere that the radar cross section of the SU-30 is as large as that of a Boeing 737, which will make it impossible for it to make surprise attacks. The PAF's F-16s are very capable fighters and since we are a defensive force, the 18 Block-52s are sufficient to counter the 36 Rafales (keeping in mind that the attacking force needs a 2.2:1 numerical advantage to have any chance of success), even if we do not count the fact that this force will be divided up between the two fronts.
Adding to this fact the JF-17 roughly matches the F-16 in aeronautical performance, we are quite secure with our fleet of JF-17s and F-16s guarding our airspace from any sort of aggression. One extremely important consideration for all air forces is the cost of operations for a fighter jet. As compared to a JF-17 with a single RD-93 engine, the MIG-29 has exactly twice as fuel consumption and maintenance costs with two RD-33 engines. If you take the SU-30, those costs go up to more than 5 times the per hour cost of flying the JF-17. So it is pointless to fly the more costly SU-30 if both planes are loaded with the same BVR missiles, and while the SU-30 might have a more powerful radar, the JF-17 will be covered by our Erieye AWACS systems up to New Delhi!
With regards to upgrades and induction of a 4.5th generation fighter, I believe the PAF is waiting for the Chinese jet engine program to mature, before it makes any decision. If the Chinese can mount an indigenous engine on the J-10, that will be a priceless addition to the PAF as it will free Pakistan from any foreign policy hindrances that it might face in the purchase of western jets. Almost all of the current choices are very expensive, but more importantly, the western countries are known to influence the buyers, which is not a good thing. The PAF is also closely looking at the 5th generation fighters of China, which will then become a huge headache for our archenemy.