Yesterday was at the counter next to me in Delhi immigration and used her PIO card. The BoI officer gave her the usual 'get an OCI card' speech and she challenged him if this was really necessary and when the PIO card would be invalid. Since there was not much going on the officer loudly asked his supervisor (across three counters) what the policy was. He responded that there is no official circular so far to that topic. They are supposed to remind people to convert to OCI but old PIO cards remain valid until further notice.