I kept myself from saying this for a long time because there are some great Pakistani guys here who I don't want to offend, but now I have to say it.
1- Pakistan didn't design JF17. It is an old soviet design that China copied and lets Pakistan produce some of the parts. Hence I doubt that Pakistan could provide any knowledge in TFX that we don't have already.
2- JF17 is barely even a 4th gen fighter. It is closer to a 3+ as Bismarck said. It is far from meeting our requirements. I am sure most Pakistani guys in this forum know that if Pakistan had a choice even they wouldn't buy it.
3- Why would we even consider JF17 when even if all else fails we can just produce more F16s? What advantage does JF17 have over F16 (especially for us) except the cost (which I don't think will be much lower due to the air force compatibility issues as
@YoungTurk01 mentioned)
And don't get me wrong, JF17 is a very good fighter, for the right people. It is very cost effective and should be the first choice in the world for countries that are getting jets for the first time or have more important priorities than air defense. For us, it is just not right.