I think an interesting question here is the consequences for nuclear proliferation without the A. Q. Khan network. Iran, Libya, and North Korea all bought technology and components from Pakistan. The North Korean weapons were based on plutonium, so this probably doesn't have a big effect there. But the Iranian program (such as it is) is based on uranium enrichment. I'm not entirely clear on where they got the technology, but the centrifuges Iran is running use the same technology as Khan's stolen URENCO designs.
What does Iran do without Khan? More generally, what is the state of international counterproliferation efforts without an example of a genuine nuclear black market? My guess is some kind of market would still emerge - there's a demand and someone will try to fill it. But it would be very different without Khan, although I'm not sure precisely how - maybe based on a different fissile technology. I'm not sure where this would go, but it could be interesting...