Yup, right now with two 6th Gen planes flying, can India even realistically match that level of tech in next 20 years? No. By then God only knows what China will have developed.
IAF missed a big trick here. They could have got the F-16 production line cheap off Lockheed who were willing to set up all global F-16 production in India and they could have got Rafale line 20 years ago.
If they had done that HAL would now be churning out 1 Sqd of Rafales and 1 Sqd of F-16Vs every year, IAF would be a very modern air force with compatibility with SE Asian and Gulf Air Forces. Back in the 70s and 80s they had two lines going for Jaguar and MIG-21 and churning them out like hot cakes, PAF at one point (pre F-16) was stuck with F-6s and Mirgae IIIs. How times have changed.
Not only now have the MIG-21s been retired and not replaced, but SU-30 is suffering from servicability issues and soon block obsolesence. Rafale order alone will simply not cut it. I see IAF going down to 22-23 Sqds in 5-10 years