well there are around 70 F-16s in Pakistan Air Force’s service, of which only 18 are the modern F-16 (C/D), while all the other ones are the old F-16 (A/B) variants which belong to the class of 80s. These (A/B) variants of F-16 in PAF's service lack modern sensors, avionics, electronic warfare systems and a superior air to air fighting capabilities. So basically our whole air defence system is depended on those elite fighter jets (F-16 C/D) that are only 18 in total lolz, and we have to beg for their spare parts too.
So seeing no future with F-16s, PAF had to start its own Fighter Jet programe named F-17 (one step ahead of F-16), which was later renamed to JF-17 Thunder. The JF-17 was designed in F-16's "Block-building" style which means the engineers can modify and replace its sensors, avionics, radars, engine, missile capability etc with more advanced equipments time to time without modifying the structure of the aircraft.
So out came Jf-17's block l and ll in quick succession of time. While the block l was a below average aircraft, the JF-17's block ll was considered a good lightweight aircraft. Now PAF is going to induct block lll which is said to have AESA radar and game changing PL-5 beyond range BVR misiles. Though Block lll is better than F-16's (A/B) variants but still it lags behind in many technology related aspects from F-16's C and D blocks. So we can safely say that PAF's direction is right and Thunder is slowly gowing into a deadly fighter jet and its block IV and V will be as deadly n lethal as F-16's latest Block D.
And let's keep in mind that india is indicting 2 squadrons of French "Dassulat Rafale" (45 aircrafts) that is said to have uppper hand over F-16's latest block D. But Rafale is too expensive, costing India 200 million dollars per unit, whereas Pakistan is focusing on indigenously made JF-17 jet that comes at a price of 28-30 million. A fielding of 4 Thunders Vs 1 Rafale will be an interesting battle.