Hurd has failed after many years to produce a kernel even nearly as complete as Linux.
I would be fascinated if Hurd could get the same sort of developer momentum to be comparable to Linux. A completely new (as in 1.0 released) and usable FOSS Unix-alike would be quite welcome amongst Linux and the BSD's I think.
Linux was initially written and released by one guy.
Linux obviously gained a wider team while Hurd languished, but it's still interesting that GNU's kernel efforts started with far more initial human resources and were still quickly overshadowed by Linux.