As per ACM interviews PAF has initiated a plan for phasing out F-16s with a 5th gen aircraft and research studies and human resource development initiated. Could be a joint venture for which Pakistan will be a late partner but no other details released yet, speculations are hinted towards J-31, so this is post 2025. So F-16s will not be replaced by newer F-16s, they will only get rebuilt and upgraded in Turkey as they get old to keep them flying longer. TAI is working on a locally developed F-16V type upgrade for its own fleet so that is a likely future candidate.
In the immediate future PAF will only get used F-16s and JF-17s. PAF will restart negotiating for new F-16s as well but with a lower more competitive price. FMF subsidized hardware is always overpriced for rewarding US manufacturers and since US will no longer provide financial assistance, new prices will have to be competitive. Hence the reason why PAF opted out of current deal.
Regarding Tejas and JF-17 difference. JF-17 got some upgrades when it entered Block-2 stage along with composites. Comparisons made everywhere are for Tejas Mark-1 Vs JF-17 Block-1 but the current production versions are Tejas Mark-1 and JF-17 Block-2. So the advantages in composites, avionics and radar are gone now. Tejas has newer Mark-1A and Mark-2 planned but has some catching up to do in terms of matching timeline. There is a very real possibility that JF-17 Block-3 will be operational before Tejas Mark 1A & 2.
From Wiki
ELM 2032
Radar Range 100km (5m2 size plane)
KLJ-7 V2
110 km (for RCS of 3 m2) (V2), or
140-150 km for RCS of 5 m2 (V2)
The ELM 2052 is intended for the Tejas but China already has access to it and its one of the two AESA contenders for JF-17 Block-3.
http://www.defensenews.com/story/de...-strongly-resembles-israeli-product/32108793/
Regardless of all other issues, my advise for HAL would be concentrate on production rate. It needs to set up additional factories for making at least 25 aircraft per year if it hopes to keep Tejas a relevant aircraft to replace obsolete jets in time.