The OpenBSD team is still developing the Xenocara X11 system, though AFAIK they aren't particularly adding features because the system is feature-complete (they aren't adding features to relayd either but it's not "abandoned" in any sense: as much as it conflicts with the CADT philosophy it's actually fine for software to be mature).
While I don't like making predictions, if I had to guess I'd guess that in a decade's time the OpenBSD team will be maintaining the upstream display server for most Linux distros just like they maintain the encrypted shell and the BGP server for them.
While I don't like making predictions, if I had to guess I'd guess that in a decade's time the OpenBSD team will be maintaining the upstream display server for most Linux distros just like they maintain the encrypted shell and the BGP server for them.