It is largely if there is someone interested in maintaining the port. My favorite port is the luna88k an obscure Japanese unix workstation/server from the early 90's. I don't know how common they were in Japan, rare is my guess, and non-existent elsewhere, but there is one(only one as far as I can tell) dedicated Japanese developer willing to put the work in to keep it current. and every release a month or two after the official release he announces that the package build is done(it takes that long on the hardware).

I don't know how many users of luna88k there are, I don't frequent anywhere near the same ecosystem they would, but have never seen one, So from my point of view it is one person making releases for himself and I love that dedication. I don't have, nor do I want a luna88k, but it great that it exists.

So as far as I can tell that is all it takes to have a published obsd port, one person willing to put the work in.