I think the last major upgrade to Mirage fleet was ROSE till 2003, its been almost 15+ years now. Due to older frames and cannibalization of aircraft for spares, it doesn't make sense to keep upgrading the aircraft. Minor changes like IFR probes are acceptable. PAF is not tilting towards J-10 also, EFT cannot be had in large numbers if its even possible to form the line up. JFT is replacing F-7 P, so Mirages still have a decade or two to go until some replacement is found.
A major infrastructure of PAF Mirages is placed at a AFB Rafiqui, Shorkot and then AFB Masroor. So the replacement aircraft will be placed at these bases. Due to nature of specialized roles of 25th and 27th squadrons, modern strike aircraft are required. 15th Sqd is also Tactical Attack, while 7th Sqd is mix of strike and air superiority, so definitely 4 x Sqds worth of a modern jet are required. Ra'ad Capable aircraft could be Chinese or French. Rafale is out of equation, Mirage-2000 option may not be exercised. EFT or SU-35 or any other which comes close to specs, otherwise wait for induction of stealth aircraft to take over strike role.