The Jf-17 is at the end of its development cycle. there is not much more you can really do with it as an airframe. its a bit like putting 4th and 5th gen avionics and features on a Mig-21 airframe, yes technically possible but not really the best use of resources or an ideal outcome.
Pakistan would be better off acquiring a squadron of the Air Force version of the J-35 from China. otherwise you aren't going to keep pace with the regional developments. The indians still haven't gotten their hands on a 5th Gen fighter, and the AMCA is like much further away, in terms of acquiring quality to counter the quantity advantage for India, that would seem to be the way, especially in BVR combat.
With a better engine on the horizon, the airframe could be modified to bring the wheels outside of the fuselage and further outward, similar to the Gripen E, allowing for more weapons (such as BVR missiles) to be carried under the fuselage in recessed stations. The design could also be slightly modified to harness the added thrust to allow the plane to achieve supercruise, and the addition of CFT could allow the plane to stay supersonic longer, allow the fighter to impart additional range to its BVR missiles from a higher altitude and at a faster speed, similar to how the F-15 can “boost” the Aim-120D to its limits. Gripen is a comparable aircraft that really shows the limits of what a 4th Gen platform in the same weight class can do. We shouldn’t discount how much further the JF-17 can be modified, especially considering our limited budget and the need to keep pace for our own needs in an affordable manner as well as offer the best 4th Gen platform in the light class to as many customers as possible.
Options should open up when the WS-19 is fully ready, with a max thrust around 120-125 kn, and better RAM technology will be affordable enough and durable enough (ease of maintenance) to put on the JF-17. Better datalinks and improvements in sensor fusion (between new IRST pods, the on board AESA and EW/ESM suites) can also allow the fleet to employ better tactics against an evolving adversary.
As the backbone of the PAF for decades to come, the JF-17 should be pushed to the limits of its design as a 4th generation light fighter, but with our budget in mind.
If we get our economy in order, all the lessons learned in improving the JF-17 can be applied to the next Gen aircraft and improved upon.
P.S. as the PAF looks to one day not just procuring but domestically producing a next gen fighter, it could begin by producing the JF-17 with the latest technologies, to lower its weight as much as possible, and made the aircraft life span as long as possible, similar to how the J-35 is being produced. So by the time a 5th Gen fighter can be produced domestically, the Kamra factory will have had years of experience.