USA government has blocked the release of Bell AH-1Z Viper attack helicopters which were built for Pakistan. Currently these helicopters are stored in Amarillo Texas. USA government also block the engine sale to Pakistan for T129 ATAK helicopter deal with Turkey. Do you think they will sell F-35 to Pakistan? One things is for sure, there will be on F-35 for Pakistan in next 10 to 15 years.
USA is a super power, no one can force them to pay CSF fund to Pakistan. If they agree to pay CSF fund, we can request new F-16 but It doesn't mean that they will sell us those. If USA agreed to sell F-16, it will probably be scale down version with lower end radar, etc.