Turkey isn't an "Advanced third party". They have put together kits of F-16s, yes, but they have no expertise in making aircraft at all. They do however have the cash. But why would they get in on this, when they have access to modern jets.
China ALONE has the resources, and it is doing it. It does not need Pakistan or Iran. We can request China for whatever China makes, and chances are we'll get it. So really, there is no need to attempt to design and manufacture our own modern fighters, and waste precious $$ on something uncertain.
Given our current financial and technical situation, and our relationship with China, the best course of action is to develop our fighter MAINTENANCE and SUBSYSTEM industries, so we can maintain our fighters, and modify/tweak them as we see fit. Which is also exactly what we ARE doing today. We have fighter rebuild factories, we have our own weapons/avionics research labs, etc... with the JF-17, we'll be even more self-reliant on maintaining our fighters.