That 15-16 m plane sounds like an indigenous 4++ gen f16 V80? (F16 length is 15.06m and the wingspan is 9.96m.)The most logical thing to do is to develop two fighter aircraft with one domestic engine solution. Hurjet will fly with a foreign engine and serial production of trainer variant will commence by 2025/2026. Develop a Hürjet Fighter variant with a length around 15-16m and modify the fuselage and wing to make it more agile. By this way, instead of looking for a different national engine solution that will cost additional R&D money, we could integrate national 30000lb turbofan that is developed for Tf-X.
But this is the logical way forward. One engine 2 planes.
Only reservation I would have is the fact that we need light attack planes with Aesa radar soon. Hurjet with a 20000+lbf engine would have given us that, before 2025-26.