I'd be surprised if the PAF doesn't at least ask for the F-16V upgrade for its 18 Block-52+. But I think upgrading the remaining F-16s might be tough, the Block-15/OCU/ADF airframes are nearing the OEM-stated airframe life.
Seems the approximate cost of upgrading No. 5's F-16s would be $900 m, and then adding another 18 Block-72 would run $2.8 b. That's $3.7 b to get 36 AESA radar-equipped medium-weight fighters (upgrade 18, add 18).
But for that price, you could get, at best, 15 Typhoon T3s (note: I'm considering the JF-17 an independent variable, more of those will come no matter what, IMO). On the other hand, the PAF won't send a dollar to the US, not until the risk of doing so is alleviated somehow (e.g., a third-party loan).