Have you considered restarting the Hurd again, using Minix 3 instead of Mach?
MINIX 3 is a free (BSD license) operating system designed to be highly reliable, flexible, and secure. It is based on a tiny microkernel running in kernel mode with the rest of the operating system running as a collection of isolated, protected, processes in user mode. It is POSIX compliant and can run bash, emacs, gcc, gdb, the X Window System, etc.
The Debian project showed that it's possible to have a GNU system on top of the FreeBSD kernel. Would producing a GNU/kMinix system be more realistic than the Hurd becoming a production-ready, superior kernel?