I've got one machine where I can't install Gnome, since it keeps pulling in systemd beside having the gnome mix-in enabled:
$ epro
=== Enabled Profiles: ===
arch: x86-64bit
build: current
subarch: native_64
flavor: desktop
mix-ins: gnome
When I run "emerge -p gnome-light", I a lot of blocking packages:
[blocks B ] sys-apps/sysvinit ("sys-apps/sysvinit" is blocking sys-apps/systemd-236-r5)
[blocks B ] >=sys-apps/systemd-197 (">=sys-apps/systemd-197" is blocking sys-auth/nss-myhostname-0.3)
[blocks B ] sys-apps/gentoo-systemd-integ