Hi Jian Ping,
For your information, Cyclone IV devices still in active status. It should not be obsolete within these few years but the life cyclone is depending on its order volume. You can subscribe to our customer notification mailing list at below link so that you can be notified when there is any changes/update in future.
https://www.intel.com/content/www/us/en/programmable/support/quality-and-reliability/pcns-and-adviso...
Thank you
Regards,
Chia Ling