In fairness Tejas is more or less similar to JF-17. Both will be likely in service for a long time facing eachother. Now that the Tejas has problems, mostly the never ending delays and mostly self-inflicted, it is true, but i guess it makes sense from IAF point of view to keep investing in it just like PAF and CAC will likely do so for JF-17/FC-1. Tejas Mk2 variant might even put it a bit ahead of the JF-17, though it is a bit unclear atm if the PFX program would be a sort of JF-17 Mk2 to even things out.
I would imagine the PFX to be like the Tejas mark 2 in getting an engine change. It won't need canards because unlike the super light Tejas its planform would work pretty much as is with the engine change and upgrades to avionics.
Putting canards to the original design while incorporating a bit more powerful engine is a testament to the bad original design that had little future-proofing in the LCA.
Both programs would be going from an 85kN engine to one around ~100kN:
F-404 to F-414
RD-93 to WS-13E or WS-21