If you ran an virtualized version of an entire traditional kernel, you'd have a hard time with performance. So that's not what you would be doing.

Go, read the old exokernel papers (see https://en.wikipedia.org/wiki/Exokernel#Bibliography, especially http://pdos.csail.mit.edu/exo/theses/engler/thesis.ps). They got nice performance improvements out of running their equivalent of unikernels. It's exactly because they can cut through all the layers of one-size-fits-all abstraction.

They also address IPC.

(This reminds me, I should go and re-read how they actually did IPC.)