Unix is NOT the be-all, end-all definitive operating system. Linux is NOT even the be-all, end-all Unix (or Unix-like). There is A LOT of research left to be done in operating systems / kernels and many many years of evolution to come.
It's a shame that it is SO HARD to build the ecosystem required to launch a kernel. New ideas are hard pressed to gain traction.
Making people want to use it is hard, as most apps people want are boring to write and/or trapped in the poor design decisions of the past (e.g. POSIX).
reference - http://www.cs.vu.nl/~ast/reliable-os/
It would be interesting to see how the original Mach microkernel runs on modern hardware. At the time, the context switching of the Mach kernel was making performance poor. But this was on 300/400 MHz machines.
They were writing a sort of microkernel, that only multiplexes/protects users from each other, but exported the raw hardware interface to userland. The abstracting part of the OS would be implemented as (possibly shared) shared libraries.