Hi Siddesh Parab,
Thank you for contacting Intel Community. Please be noted that EPCS4SI8N was discontinued according to PDN1708:
Cyclone III devices currently are in mature life cyclone phase, Although they are not be discontinued at this moment. Anyhow, the life cycle is depending on its order volume.
At the meantime, you can subscribe to our customer notification mailing list at below link so that you can be notified when an Altera device is going to be discontinued.