Bruh .. we still use pechoras.. I'm sure we will seek to relife them rather than throw them away.
I'm not sure .. but isn't the akash and akash s to complement the phechora while the akash ng will replace it ?
Basically S 300 has replaced pechera long back in Russia etc. And then S 400 and now soon S 500.
We use them because we still have it and they are still useful .
Basically we will create multiple layer of defense long range missile short range medium range and very large like 400-600 km etc.
And eventually we will integrate them into a system like S 400 S 500 etc works.
Now instead of Spyder , Astra will be used for short range in future once it matures.
Remember Akash doesn't have seeker like Spyder or Astra Barak etc. It is dependent on ground based pesa radar completely for guidance. May be in future we may soon see a version with seeker. But that's fine a cheaper system that can be produced in mass will also be needed we cannot put expensive Astra or Spyder like system everywhere.