The number of segments is not dynamic, unfortunately, so it needs to be planned ahead. Additionally, in Infinispan 8.2 we are going to be recommending a higher ratio of segments / node (32). You cannot really plan for indefinite growth, so my recommendation is to stay on the "comfortable" side, while still being reasonable, about the expected maximum number of nodes in the cluster.
Okay, agreed. We need to plan ahead, and as per your comment I can conclude that the recommended multiplication factor will be 32 from 8.2 onward i.e. segement = 32 * cluster size