We still need western tech to counter Rafale if no Vipers then IK s Susrals UK with EF jetts I don't see any issue along good terms in financing
If new off-the-shelf fighters don't come, the focus will shift to high-end SAM systems and new ISR assets.
The CSF and FMF components probably can't cover more than 50% of a robust F-16 package (36 Block-72 and F-16V upgrades for our entire fleet will run up to $6 b easily). So, at least half that will be our own funding.
If there are no F-16s or Typhoons in play, then we'll probably talk to Turkey to get in on their joint-project with MBDA/Eurosam, i.e., SIPER.
On top of that, I can see the PAF going for the Saab GlobalEye or Erieye ER in order to give the JF-17 a massive network-enabled warfare boost, plus some stand-off range jammers, refueling aircraft, etc.
Relatively speaking, you can get quite a few support assets...e.g., Saab's GlobalEye costs $250-300 m per plane; stand-off jammer via Turkey might run $75-125 m per plane; a KC-390 with 15 years support package is around $200 m per plane, a A330 MRTT is $250-300 m.
For $3 bn, we can stock up on 3 new GlobalEye AEW&C, 3 new jamming aircraft, 6-8 KC-390 MRTTs OR 3 A330 MRTTs.
That said, new F-16s or not, upgrading the current ones is definitely on the cards. I can't see the PAF sitting pat on this one, it's just the natural outcome of things and they might even break the rules (e.g., get the Turkish program) to get it done if the US drags its feet. As we get closer to Project Azm and have more JF-17 Block-3s in the fleet, the care for US sanctions will wane.