I'm not sure this was the point of parent, but anyway, why would you want something like that? It's not like sysvinit has any redeeming feature, and you would still want to have systemd .service files. I could understand an argument like "/bin/systemd does too many things and ought to be split up more", but the rationale for having bad old sysvinit launch /etc/init.d/systemd.sh escapes me. Not to mention that you definitely don't want both systemd and sysvinit to attempt to launch scripts in /etc/init.d, when they don't have a .service...