Wishful thinking in the 90s of hoping embargoes would be lifted and F-16s would be released was the reason decision to upgrade Mirage took too long and used Mirage F-1s not acquired when PAF had the opportunity.
Again advent of F-16 Block-52s and MLU upgrades negated the chances of acquiring J-10s when that became available.
However in the end I think turned out well for PAF. PAF will soon have just two major platforms JF-17 and F-16 along with a handful of Mirage Rose or F-7PGs. With a new 5th gen platform joining in 2021-4. It will become a very lean force.
PAF has a defensive setup when the aircraft inventory is observed. In own skies, PAF is a lean force.
F-7P/PG is a point defence or escort fighter. It should have been completely retired by now or in coming couple of years, which was envisioned when JF-17 was brought into perspective. It is limited by many aspects. Upgrading it has reached its limit. It is very effective in a dog fight when its complementing F-16 and JF-17 to make up numbers in the air. Put drop tanks to increase range and compromise on its payload. The air frames are relatively new for PG versions. Bangladeshis have a put 7 hard points on it to make it more potent for BAF. But over all this aircraft in PAF is in front line service instead of reserves because no other alternative has been acquired yet.
Mirage,Rose or non-Rose, have also reached their limitations. Their usefulness is there but their life on most frames is over. Its the lack of choice that PAF has which is why these planes are still in first line of duty for strike role after F-16. PAF once went on a world wide shopping spree to get the Mirage-III/V body frames and planes from all parts of the world. This brings the choices that PAF had to replace these aircrafts early which would never had increased their numbers beyond 120 or so and probably would have also kept the F-7P/PG population down just like A-5 and retired them quickly.
Mirage-2000 probably if acquired in 80's or 90's would have even given PAF a great opportunity to bring a aircraft in air which is comparable in capabilities to F-16. The dependency on F-16 would have not have been so high as it is now currently. Instead of Mirage III/V in hundreds, PAF would have acquired Mirage-2000 in hundreds. The 3rd gen aircrafts like F-7 and Mirage II/V would have been retired and PAF would be operating only 4th gen with JF-17, F-16 and Mirage-2000. In fact PAF could have got rid of F-16 completely from its inventory instead of maximising its numbers in lieu of Mirage-2000. This move could have brought J-10 in PAF and PAF would be fielding the first AESA with FC-10 or J-10B.
Even if considering that F-16 nullified the possibility of J-10 in PAF and that the cash in PAF hand can be spent on 5th gen aircraft, the numbers and limitations of 5th gen aircraft will again put F-16 to take the brunt of the burden of PAF. 5th Gen will be two squadrons at most to start with and God knows when PAF will increase them from two squadrons to 4 or 5. The payload carried by 5th gen aircraft while retaining its stealth capabilities, is still small, but it will give two advantages to PAF.
1. Offensive capability of PAF will be increased ten folds.
2. PAF will win the 5th gen induction race from IAF.
The cost of operation and maintenance of 5th gen can still be considered more than 4th gen fighters.
PAF could be eventually planning of:
4th gen aircraft: F-16 and JF-17.
4.5 gen aircraft: JF-17 Block 3
5th gen aircraft: J-31 probably.
JF-17 will be the maximum numbers that PAF will field, a light category. F-16 is a medium category, reaching 100 mark seems very difficult now and then J-31 will be a stealth category. A medium or heavy category of 4.5 gen aircraft like SU35 or EF2000 would have given a fresh lethal look to PAF before any 5th gen is inducted.