"That, needless to say, is a recipe for irrelevance and, eventually, disappearance."
In the last eight+ years I've used OpenBSD extensively as the networking and firewall core for smart grid networks. I can, with confidence, say that 100% of the smart grid transactions on at least two $Billion+ utilities on at least two continents flow through OpenBSD servers.
We evaluated the full gamut of Cisco, Fortinet, and other Firewall technologies, but, from 2004 through 2010, only OpenBSD had the functionality and failover that we were looking for for < $100K/appliance. (And, when you want two for redundancy, plus another two for your DR center - Four appliances add up). It almost pained me to see how low-end a server could handle hundreds of thousands of IPv6 UDP states compared to what Cisco would have charged. (Note - and, regardless, Cisco didn't, until recently, handle IPv6 in fault-tolerant Active-Hot-Standby mode on their ASA platform)
For those that have a lot of experience with OpenBSD - the continued rock solid stability, almost 100% complete (and useful) _systems_ documentation (as opposed to the utility and library documentation you get on a linux system), consistent startup/configuration for 10+ years, plus, of course, very mature pf, makes the platform a continuing highly relevant product, that will not disappear for many years to come.