You both should take a look at the Second to None article about how the PAF looked at the F-20, even after buying the F-16.
secondtonone.com.pk
In the early 1980s, AHQ didn't think it could afford enough F-16s to replace the F-6s, so it looked at a lightweight multirole fighter. The US offered the F-20 and the PAF sent a team to check it out, citing a potential order of 100 units. Based on what they saw, the PAF team liked the F-20, but they couldn't complete the tests because Northrop was still integrating weapons to the F-20 and, sadly, they lost most of their prototypes. The program got shelved.
I bring this up because, for its time, the F-20 was filling the exact niche of the JF-17. The one air force (i.e., PAF) that needed a lighter multirole complement to the F-16 could have been the launch buyer, yet neither AHQ nor Northrop thought the PAF alone could keep the F-20 alive.
Seeing this and, frankly, the relative lack of traction of other similar fighters (e.g., Gripen), I wonder if the JF-17 is just too niche for most countries. This is not an indictment on the JF-17. There aren't many air forces like the PAF that expect to fight heavily in the air - and alone without allies. Interestingly, the countries that have similar issues as the PAF have lightweight fighters of their own, e.g., India (Tejas), Sweden (Gripen), South Korea (FA-50).
For most other countries, air power is a strategic asset meant to provide deterrence, not an integral tactical tool. So, they prioritize things like range, payload, and, increasingly, stealth more so than low operating costs and numbers. Others, like a small NATO state, expect to operate in an alliance, so it just needs enough assets to deliver its share (e.g., Romania and 1-2 F-35 squadrons).
By joining NATO, I think the Swedes will also move away from the doctrines that led to the Gripen and, instead, favor a larger and more strategically impactful NGFA. They'll likely bank on their collaborative alliances with the UK and other North Sea neighbours.
Ironically, I think the remaining country to find true value in the JF-17 is Iran. They seem to understand the value of lightweight tactical assets in numbers and would appreciate how much each single JF-17 (especially Block-III) offers in versatility. However, I think they also have it in them (maybe in a few years) to develop their own solution.