Seems to me there are several options:
1) run the last version of gnome that works without systemd
2) run a patched later version of gnome from another distro that works without systemd
3) don't use gnome, use a different desktop environment
4) fork/patch gnome and remove the dependency yourself
systemd can't take any of those away from you.
If the people actually working on gnome want to add another dependency to gnome, that's their business, is it not? It doesn't break the existing, pre-systemd versions of gnome.
