Beyond 2030, if IAF are inducting and HAL is making 4/4.5 gen aircraft something has gone very wrong. Plans that look good on paper now will be obsolete in 10 years.
The generational lag in Tejas development means that it's main MK1A version will start coming of the factory line when one of it's main rivals (JF-17 Block III and J-10C) will come to the end of their production lives. China and Pakistan will move on to purely 5th gen, in case of China, Europe and US, possibly 6th gen.
10 years from now IAF may well induct first new Tejas MKII sqd with much fanfare, trust me when I say China will have 6th gen by then, PAF will have either J-31/KAAN/PFX or some mixture f all three
With Tejas MK1A and MK2 you will have capable planes that will not be able to see, locate or target many of their enemies, and in many cases be outranged by missiles.
As with Arjun and Rustom drone, India is making a decent product a generation too late. No shame in that, India is still learning and should credit it's engineers and designers, but it's air force and pilots require state of the art.
Three painful steps can remedy this situation
1) Dump Tejas MK2, expediate AMCA. Literally put all your aviation resources into this
2) Dump Russia, lose S-400, promise whatever you need to with the US and buy 120 F-35
3) Like Japan that has a very robust aviation and technology base, go for a joint 6th gen project with Europe (either the Franco/German project or the British/Swedish/Jap project)
All of the above will massively benefit Indian industry and learning. If you do not do this, expect to face the very best Chinese and possibly European 5th/6th gen tech in the hands of your enemies in 10-15 years while you are flying Tejas and SU-30s....