There have been 63 Nayanars who are inseparable from Shaiva Siddhanta. I was just wondering whether there can be more Nayanars or not? If Not why can't there be? If yes, what is the procedure to become a Nayanar?
As per Periya Puranam(Epic in which the life history of Nayanars were written), at Tiruvarur Sundaramoorthy Nayanar recited the names of all sixty-three Nayanars,including those who lived before him, and who will live after him. This recitation is called Tiruttondar-Tokai. In it, he refers to himself as the servant of servants of these saints. There he mentioned only 63, so we don't have more than that.
The Nayanmars (also referred to as Nayanars) written in Tamil as நாயன்மார்கள், means "hounds of Siva",were a group of 63 saints (also saint poets) in the 6th to 9th century who were devoted to the Hindu god Shiva in Tamil Nadu. They, along with the 12 Alvar saints, (who were Vaishnavites) influenced the Bhakti movement in Tamil Nadu. In the 10th century the head priest of King Raja Raja Chola I of Thanajavur named Nambiyandar Nambi compiled the work of these 63 Nayanmars.
The Nayanars were from various backgrounds, including Channars, Vellalas, oilmongers, Brahmins, and nobles. Along with the twelve Vaishnava Alvars, they are regarded the important saints from Tamil Nadu.
The Hindu revivalism which flourished between the 6th and 13th centuries in India produced many saints and scholars. The Nayanmars were among them.
There is no monastic order of Nayanmars, into which one can be initiated. Also the life of a wandering minstrel is just about impossible in the modern era. since the 9th Century CE there have been no further Nayanmars and the Bhakti Movement of the times of Nayanmars and Alvars no longer exists.
to answer your query briefly - there will be no more Nayanmars because they were not a religious sect, but independent saint - Scholar poets devoted to the worship of Lord Shiva.