Title: Desktop profile switching USE default to elogind
Author: Andreas Sturmlechner <email@example.com>
Modern desktop environments make use of PAM session tracking for users, login
sessions and seats.  The most user-visible part of that is device and file
permissions management and reboot/shutdown handling without superuser rights.
Users with systemd can stop reading here and continue with their daily
ConsoleKit2 is unmaintained upstream for more than two years . There are
many longstanding bugs and papercuts with consumers that aren't being fixed,
not least because these code paths receive very little testing.
Enter the elogind project , which is a standalone logind implementation
based on systemd code, currently maintained by a fellow Gentoo user. We have
had sys-auth/elogind available in Gentoo since the beginning of 2017, and
meanwhile it has gained support  in KDE Plasma, Gnome , Cinnamon, MATE
and Xfce, as well as most other former consolekit consumers.
Consequently, the desktop profile is switching away from consolekit to
elogind. Users of sys-auth/consolekit who selected a different profile should
consider doing the same. A guide is available . Migration is easy, but any
existing consolekit session will be broken, and elogind will only begin to work
Rely either on the profile, or set USE="elogind -consolekit" in make.conf
yourself. Make sure there is no consolekit debris in /etc/portage/package.use:
# grep -R consolekit /etc/portage/package.use
Rebuild all affected consumers and remove sys-auth/consolekit:
# emerge --ask --changed-use --deep @world
# emerge --depclean consolekit
Optional, but recommended in case of trouble such as missing reboot/shutdown
capabilities in the display manager:
# rc-update add elogind boot
For users of ~/.xinitrc instead of one of the supported DMs, do not forget to
update accordingly (ck-launch-session is gone without replacement).
PS: Subsequently, this will lead to the last-riting of sys-power/pm-utils 
which is dead even longer than the original ConsoleKit(1) project. KDE Plasma
users sticking with sys-auth/consolekit are then going to lose suspend from
GUI without superuser rights.