I have noticed openrc package after I have upgraded to 14.10.
So, is it possible to get rid of upstart and systemd(logind, udevd) and upstart and move to it?
I have installed the package and have rc-* commands, but /sbin/init is still upstart and systemd components are still there. I have tried to set init=/sbin/openrc but pc then failed to boot, printing something about deadlock resolving.
It seem that the question holds the answer itself. As @muru pointed, openrc does not replace /sbin/init, but works in pair with the init system already running.
So the correct answer for ubuntu 14.10 and higher, is just sudo apt-get install openrc, reboot and see your system running a zoo of multiple init systems.
PS: After installation, boot time increased in about two times, and after removal, it just have removed half of the packages as well.