Brother JF17 will not win you a war / cant protect and as you mentioned earlier 5th Gen is little away .In my last comments i have mentioned may be this money is needed for partnering the J31 program remmember J31 is looking an international partner .In my view PAF is evaluating things but considering F16 and JF17 = 150 is not a deterrent force ,till 2025 F16A/B MLU will need another service extension or simply we have to ground them .
Numbers by 2020
JF17 = 150
F16 = 80-100
Still room for 100 fighters and at the same time F16`s need replacements in my view
2020 - need 200 fighters (Jf-17 150 )
2025 - need 50 fighters brand new (replacement of F16 better to replace with single engine 4++)
2030 - All F16s needed to be replaced by platform