I installed KDE last night and the Gentoo Wiki recommended me to install consolekit. Today I read that consolekit is deprecated
"ConsoleKit is currently not actively maintained. The focus has shifted to the built-in seat/user/session management of Software/systemd called systemd-loginctl"
that it is "not actively maintained" does not mean that it does not work. I think currnetly there is no need to look for an alternative. KDE works fine with the current version of consolekit.