I am unaware of any reasons why Wayland won’t come to OpenBSD. Last I checked, progress towards the possibility of running Wayland compositors on OpenBSD had been progressing slowly. OpenBSD seems to support KMS these days, as well as DRM. I don’t know if OpenBSD will adopt evdev, but I don’t think it would be a giant logical leap unless the maintainers are diametrically opposed.
If OpenBSD is unable to transition to Wayland, that does call into question what it will do in the future. My understanding is that Xorg maintenance basically only extends to Xwayland use cases, so it seems like a fork of Xorg or an alternative would be needed to keep things going in the longer term.
X.org maintenance consists of merging drivers written by GPU companies. The software itself has been totally finished for many years. Im sure when IBM et al decide to formally relinquish control of X.org instead of pussyfooting around with this "maintenance mode" act, we'll see more progress though. Promising technologies such as Xgl were left by the wayside because X.org is supposed to be depreciated.
If OpenBSD is unable to transition to Wayland, that does call into question what it will do in the future. My understanding is that Xorg maintenance basically only extends to Xwayland use cases, so it seems like a fork of Xorg or an alternative would be needed to keep things going in the longer term.