This is partly due to it being open source and partly due to its small
footprint and stability. Code bases come and go, but the core architecture
hasn't changed in literally decades.
I guess that depends how you define "core architecture". :)
I'd say there are at least three competing core architectures for implementing Unix:
The infamous 1992
Linux is obsolete
debate between old hand respected operating system researcher Andrew Tanenbaum
and young upstart Linus Torvalds makes interesting reading.
I guess it shows that "theoretical (academic) superiority"
does not necessarily translate to success in the marketplace.
I think it's fair to say that monolithic kernels still dominate the
Unix arena, though
is built on top of the
Mac OS X
is built on the
Mach/BSD-based hybrid kernel.
Though I'd like to see the microkernel based
succeed, sadly that now looks doubtful after more than
twenty years of development -- yet another example of
the perils associated with "writing new systems from scratch".