If it has an ABI which means POSIX tools just work, I'm fine if its a microkernel. MACH was at the heart of lots of things too. We could do capabilities based OS design you name it. 9P, I don't care.

What I care about is getting an interactive shell prompt and a filesystem with . and .. and / and BOURNE shell compatible semantics, and an ability to run vi and emacs. (I am less sure plan9 people care about shell btw they went rc and then into some place I don't understand up in the 5th dimension)