Horn stems offers different feelings. The first thought coming to my mind is that it will be more and more rare in the coming years.
Most of horn stems are now coming from old stock. I personally like the idea of natural origin, to my mind, it is in perfect communion with briar and compared to vulcanite, Lucite or Cumberland, horn stems makes more sense, on an esthetical point of view.
I am working on a series of horn stems right now and hope to release around twenty briar pipes of various shapes (all from preturned stummels), I will see if people can be interested.