One of the pieces of news of the time interval is (GNOME is) Introducing stronger dependencies on systemd (via). Back in the old days, GNOME was a reasonably cross-platform Unix desktop environment, one that you could run on, for example, FreeBSD. I believe that's been less and less true over time already (although the FreeBSD handbook has no disclaimers), but GNOME adding more relatively hard dependencies on systemd really puts a stake in it, since systemd is emphatically Linux-only.

It's possible that people in FreeBSD will do more and more work to create emulations of systemd things that GNOME uses, but personally I think this is quixotic and not sustainable. The more likely outcome is that FreeBSD and other Unixes will drop GNOME entirely, retaining only desktop environments that are more interested in being cross-Unix (although I'm not sure what those are these days; it's possible that GNOME is simply more visible in its Linux dependency).

An aspect of this shift that's of more interest to me is that GNOME is the desktop environment and (I believe) GUI toolkit that has been most vocal about wanting to drop support for X, and relatively soon. The current GDM has apparently already dropped support for starting non-Wayland sessions, for example (at least on Fedora, although it's possible that Fedora has been more aggressive than GNOME itself recommends). This loss of X support in GNOME has been a real force pushing for Wayland, probably including Wayland on FreeBSD. However, if FreeBSD no longer supports GNOME, the general importance of Wayland for FreeBSD may go down. Wayland's importance would especially go down if the general Unix desktop world splits into one camp that is increasingly Linux-dependent due to systemd and Wayland requirements, and another camp that is increasingly 'old school' non-systemd and X only. This second camp would become what you'd find on FreeBSD and other non-Linux Unixes.

(Despite what Wayland people may tell you, there are still a lot of desktop environments that have little or no Wayland support.)

However, this leaves the future of X GUI applications that use GTK somewhat up in the air. If GTK is going to seriously remain a cross-platform thing and the BSDs are effectively only doing X, then GTK needs to retain X support and GTK based applications will work on FreeBSD (at least as much as they ever do). But if the GNOME people decide that 'cross-platform' for GTK doesn't include X, the BSDs would be stuck in an awkward situation. One possibility is that there are enough people using FreeBSD (and X) with GTK applications that they would push the GNOME developers to keep GTK's X support.

(I care about this because I want to keep using X for as long as possible. One thing that would force me to Wayland is if important programs such as Firefox stop working on X because the GUI toolkits they use have dropped X support. The more pressure there is from FreeBSD people to keep the X support in toolkits, the better for me.)